The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Paul C Simpson - One of the best experts on this subject based on the ideXlab platform.
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an oral selective alpha 1a Adrenergic Receptor agonist prevents doxorubicin cardiotoxicity
JACC: Basic to Translational Science, 2017Co-Authors: Ju Youn Beak, Paul C Simpson, Wei Huang, Joel S Parker, Sean T Hicks, Cam Patterson, Jian Jin, Brian C JensenAbstract:α1A-ARs play adaptive and protective roles in the heart. Dabuzalgron is an oral selective α1A-AR agonist that was well tolerated in multiple clinical trials of treatment for urinary incontinence, but has never been used to treat heart disease in humans or animal models. In this study, we administered dabuzalgron to mice treated with DOX, a widely used chemotherapeutic agent with dose-limiting cardiotoxicity that can lead to HF. Dabuzalgron protected against DOX-induced cardiotoxicity, likely by preserving mitochondrial function. These results suggest that activating cardiac α1A-ARs with dabuzalgron, a well-tolerated oral agent, might represent a novel approach to treating HF.
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The Alpha-1A Adrenergic Receptor agonist A61603 reduces cardiac polyunsaturated fatty acid and endocannabinoid metabolites associated with inflammation in vivo
Metabolomics, 2016Co-Authors: Monte S. Willis, Megan D Montgomery, Paul C Simpson, Amro Ilaiwy, Brian C JensenAbstract:Introduction Alpha-1-Adrenergic Receptors (α1-ARs) are G-protein coupled Receptors (GPCRs) with three highly homologous subtypes (α1A, α1B, and α1D). Of these three subtypes, only the α1A and α1B are expressed in the heart. Multiple pre-clinical models of heart injury demonstrate cardioprotective roles for the α1A. Non-selective α1-AR activation promotes glycolysis in the heart, but the functional α1-AR subtype and broader metabolic effects have not been studied. Objectives Given the high metabolic demands of the heart and previous evidence indicating benefit from α1A activation, we chose to investigate the effects of α1A activation on the cardiac metabolome in vivo. Methods Mice were treated for 1 week with a low, subpressor dose of A61603, a highly selective and potent α1A agonist. Cardiac tissue and serum were analyzed using a non-targeted metabolomics approach. Results We identified previously unrecognized metabolic responses to α1A activation, most notably broad reduction in the abundance of polyunsaturated fatty acids (PUFAs) and endocannabinoids (ECs). Conclusion Given the well characterized roles of PUFAs and ECs in inflammatory pathways, these findings suggest a possible role for cardiac α1A-ARs in the regulation of inflammation and may offer novel insight into the mechanisms underlying the cardioprotective benefit of selective pharmacologic α1A activation.
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the alpha 1a Adrenergic Receptor agonist a61603 reduces cardiac polyunsaturated fatty acid and endocannabinoid metabolites associated with inflammation in vivo
Metabolomics, 2016Co-Authors: Monte S. Willis, Megan D Montgomery, Paul C Simpson, Amro Ilaiwy, Brian C JensenAbstract:Alpha-1-Adrenergic Receptors (α1-ARs) are G-protein coupled Receptors (GPCRs) with three highly homologous subtypes (α1A, α1B, and α1D). Of these three subtypes, only the α1A and α1B are expressed in the heart. Multiple pre-clinical models of heart injury demonstrate cardioprotective roles for the α1A. Non-selective α1-AR activation promotes glycolysis in the heart, but the functional α1-AR subtype and broader metabolic effects have not been studied. Given the high metabolic demands of the heart and previous evidence indicating benefit from α1A activation, we chose to investigate the effects of α1A activation on the cardiac metabolome in vivo. Mice were treated for 1 week with a low, subpressor dose of A61603, a highly selective and potent α1A agonist. Cardiac tissue and serum were analyzed using a non-targeted metabolomics approach. We identified previously unrecognized metabolic responses to α1A activation, most notably broad reduction in the abundance of polyunsaturated fatty acids (PUFAs) and endocannabinoids (ECs). Given the well characterized roles of PUFAs and ECs in inflammatory pathways, these findings suggest a possible role for cardiac α1A-ARs in the regulation of inflammation and may offer novel insight into the mechanisms underlying the cardioprotective benefit of selective pharmacologic α1A activation.
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The Alpha-1A Adrenergic Receptor in the Rabbit Heart
PloS one, 2016Co-Authors: R. Croft Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Paul C SimpsonAbstract:The Alpha-1A-Adrenergic Receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the Alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the Alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with
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a myocardial slice culture model reveals alpha 1a Adrenergic Receptor signaling in the human heart
JACC: Basic to Translational Science, 2016Co-Authors: Croft R Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Megan D Montgomery, Philip M Swigart, Teresa De Marco, Anthony J Baker, Paul C SimpsonAbstract:Translation of preclinical findings could benefit from a simple, reproducible, high throughput human model to study myocardial signaling. Alpha-1A-Adrenergic Receptors (ARs) are expressed at very low levels in the human heart, and it is unknown if they function.To develop a high throughput human myocardial slice culture model, and to test the hypothesis that Alpha-1A- ARs are functional in the human heart.Cores of LV free wall 8 mm diameter were taken from 52 hearts (18 failing and 34 nonfailing). Slices 250 μm thick were cut with a Krumdieck apparatus and cultured using a rotating incubation unit.About 60 slices were cut from each LV core, and a typical study could use 96 slices. Myocyte morphology was maintained, and diffusion into the slice center was rapid. Slice viability was stable for at least 3 days in culture by ATP and MTT assays. The beta-AR agonist isoproterenol stimulated phospholamban phosphorylation, and the Alpha-1A-AR agonist A61603 stimulated ERK phosphorylation, with nanomolar EC50 values in slices from both failing and nonfailing hearts. Strips cut from the slices were used to quantify activation of contraction by isoproterenol, A61603, and phenylephrine. The slices supported transduction by adenovirus.We have developed a simple, high throughput LV myocardial slice culture model to study signaling in the human heart. This model can be useful for translational studies, and we show for the first time that the Alpha-1A-AR is functional in signaling and contraction in the human heart.
Baterdene Myagmar - One of the best experts on this subject based on the ideXlab platform.
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coupling to gq signaling is required for cardioprotection by an alpha 1a Adrenergic Receptor agonist
Circulation Research, 2019Co-Authors: Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Taylor Ismaili, Anaha Raghunathan, Sunil Sahdeo, Jonathan M Blevitt, Marcos E MillaAbstract:Rationale: Gq signaling in cardiac myocytes is classically considered toxic. Targeting Gq directly to test this is problematic, because cardiac myocytes have many Gq-coupled Receptors. Objective: T...
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an alpha 1a Adrenergic Receptor agonist prevents acute doxorubicin cardiomyopathy in male mice
PLOS ONE, 2017Co-Authors: Baterdene Myagmar, Megan D Montgomery, Philip M Swigart, Trevor Chan, Rajesh DashAbstract:Alpha-1 Adrenergic Receptors mediate adaptive effects in the heart and cardiac myocytes, and a myocyte survival pathway involving the Alpha-1A Receptor subtype and ERK activation exists in vitro. However, data in vivo are limited. Here we tested A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide), a selective imidazoline agonist for the Alpha-1A. A61603 was the most potent alpha-1-agonist in activating ERK in neonatal rat ventricular myocytes. A61603 activated ERK in adult mouse ventricular myocytes and protected the cells from death caused by the anthracycline doxorubicin. A low dose of A61603 (10 ng/kg/d) activated ERK in the mouse heart in vivo, but did not change blood pressure. In male mice, concurrent subcutaneous A61603 infusion at 10 ng/kg/d for 7 days after a single intraperitoneal dose of doxorubicin (25 mg/kg) increased survival, improved cardiac function, heart rate, and cardiac output by echocardiography, and reduced cardiac cell necrosis and apoptosis and myocardial fibrosis. All protective effects were lost in Alpha-1A-knockout mice. In female mice, doxorubicin at doses higher than in males (35-40 mg/kg) caused less cardiac toxicity than in males. We conclude that the Alpha-1A-selective agonist A61603, via the Alpha-1A Adrenergic Receptor, prevents doxorubicin cardiomyopathy in male mice, supporting the theory that Alpha-1A Adrenergic Receptor agonists have potential as novel heart failure therapies.
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The Alpha-1A Adrenergic Receptor in the Rabbit Heart
PloS one, 2016Co-Authors: R. Croft Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Paul C SimpsonAbstract:The Alpha-1A-Adrenergic Receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the Alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the Alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with
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the alpha 1a Adrenergic Receptor in the rabbit heart
PLOS ONE, 2016Co-Authors: Croft R Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Philip M Swigart, Anthony J BakerAbstract:The Alpha-1A-Adrenergic Receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the Alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the Alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with <1% Alpha-1A and alpha-1D, whereas Alpha-1A mRNA was over 50% of total in brain and liver. Saturation radioligand binding identified ~4 fmol total alpha-1-ARs per mg myocardial protein, with 17% Alpha-1A by competition with the selective antagonist 5-methylurapidil. The alpha-1D was not detected by competition with BMY-7378, indicating that 83% of alpha-1-ARs were alpha-1B. In isolated left ventricle and right ventricle, the selective Alpha-1A agonist A61603 stimulated a negative inotropic effect, versus a positive inotropic effect with the nonselective alpha-1-agonist phenylephrine and the beta-agonist isoproterenol. Blood pressure assay in conscious rabbits using an indwelling aortic telemeter showed that A61603 by bolus intravenous dosing increased mean arterial pressure by 20 mm Hg at 0.14 μg/kg, 10-fold lower than norepinephrine, and chronic A61603 infusion by iPRECIO programmable micro Infusion pump did not increase BP at 22 μg/kg/d. A myocardial slice model useful in human myocardium and an anthracycline cardiotoxicity model useful in mouse were both problematic in rabbit. We conclude that Alpha-1A mRNA is very low in rabbit heart, but the Receptor is present by binding and mediates a negative inotropic response. Expression and function of the Alpha-1A in rabbit heart differ from mouse and human, but the vasopressor response is similar to mouse.
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a myocardial slice culture model reveals alpha 1a Adrenergic Receptor signaling in the human heart
JACC: Basic to Translational Science, 2016Co-Authors: Croft R Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Megan D Montgomery, Philip M Swigart, Teresa De Marco, Anthony J Baker, Paul C SimpsonAbstract:Translation of preclinical findings could benefit from a simple, reproducible, high throughput human model to study myocardial signaling. Alpha-1A-Adrenergic Receptors (ARs) are expressed at very low levels in the human heart, and it is unknown if they function.To develop a high throughput human myocardial slice culture model, and to test the hypothesis that Alpha-1A- ARs are functional in the human heart.Cores of LV free wall 8 mm diameter were taken from 52 hearts (18 failing and 34 nonfailing). Slices 250 μm thick were cut with a Krumdieck apparatus and cultured using a rotating incubation unit.About 60 slices were cut from each LV core, and a typical study could use 96 slices. Myocyte morphology was maintained, and diffusion into the slice center was rapid. Slice viability was stable for at least 3 days in culture by ATP and MTT assays. The beta-AR agonist isoproterenol stimulated phospholamban phosphorylation, and the Alpha-1A-AR agonist A61603 stimulated ERK phosphorylation, with nanomolar EC50 values in slices from both failing and nonfailing hearts. Strips cut from the slices were used to quantify activation of contraction by isoproterenol, A61603, and phenylephrine. The slices supported transduction by adenovirus.We have developed a simple, high throughput LV myocardial slice culture model to study signaling in the human heart. This model can be useful for translational studies, and we show for the first time that the Alpha-1A-AR is functional in signaling and contraction in the human heart.
Kenneth P. Minneman - One of the best experts on this subject based on the ideXlab platform.
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activation of signal transducers and activators of transcription by alpha 1a Adrenergic Receptor stimulation in pc12 cells
Molecular Pharmacology, 2000Co-Authors: Hongying Zhong, T J Murphy, Kenneth P. MinnemanAbstract:In PC12 cells stably expressing α1A-Adrenergic Receptors (ARs), norepinephrine (NE) activates several mitogen-activated protein kinase pathways and causes differentiation ([Williams et al., 1998][1]). Using retroviral luciferase reporters, we found that NE also activated both signal transducers and activators of transcription (Stat) and γ-interferon-activated sequence-mediated transcriptional responses, with maximal effects similar to those caused by interleukin-6 (IL-6). UTP and epidermal growth factor had no effect, whereas nerve growth factor caused a small Stat activation. Responses to NE were blocked by prazosin and depended on Receptor density. Responses to NE were not blocked by inhibitors of mitogen-activated protein kinase kinase (PD98059), protein kinase C (GFX203290), Src (PP2), Jak2 (AG490), or the calcium chelator 1,2-bis(2-aminophenoxy)ethane- N , N , N ′, N ′-tetraacetic acid. The p38 mitogen-activated protein kinase inhibitors SB202190 and SB203580 blocked Stat activation by NE, the epidermal growth factor Receptor inhibitor AG1478 caused a small inhibition, but the phosphoinositide 3 kinase inhibitor LY294002 potentiated both responses. Gel shifts confirmed formation of nuclear factors binding to both Stat and γ-interferon-activated sequence consensus sequences in response to NE and IL-6. Immunoprecipitation experiments showed that IL-6 increased tyrosine phosphorylation of Stat1 and Stat3 in PC12 cells, whereas NE caused a sustained increase in tyrosine phosphorylation of Stat1. These results suggest that α1A-AR stimulation causes Stat-mediated transcriptional responses in PC12 cells that are not downstream of known second messenger or tyrosine kinase pathways. [1]: #ref-33
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Activation of tyrosine kinases by alpha1A-Adrenergic and growth factor Receptors in transfected PC12 cells.
The Biochemical journal, 1999Co-Authors: Hongying Zhong, Kenneth P. MinnemanAbstract:We compared the role of tyrosine kinases in alpha(1A)-Adrenergic Receptor (AR) and growth factor Receptor stimulation of mitogen-activated protein kinase pathways in PC12 cells. Norepinephrine (NE) (noradrenaline), epidermal growth factor (EGF) and nerve growth factor (NGF) caused different patterns of tyrosine phosphorylation in PC12 cells stably expressing alpha(1A)-ARs. NE increased tyrosine phosphorylation of focal adhesion-related kinase Pyk2 and a 70 kDa protein, probably paxillin, whereas EGF strongly stimulated tyrosine phosphorylation of the EGF Receptor and cytokine-activated kinase Jak2. The EGF Receptor inhibitor AG1478 inhibited activation of extracellular signal-regulated kinases (ERKs) by EGF but not by NE. EGF and NGF strongly activated tyrosine phosphorylation of Shc and caused association of Src-homology collagen (Shc) with growth-factor-Receptor-bound protein 2 (Grb2); however, neither NE nor UTP caused substantial activation of the Shc/Grb2 pathway. NE, UTP, EGF and NGF all increased tyrosine phosphorylation of Src, and this was inhibited by the Src inhibitor PP2. However, PP2 inhibited ERK activation in response to NE and UTP, but not in response to EGF or NGF. PP2 also completely blocked NE-induced PC12 cell differentiation, but had no measurable effect on NGF-induced differentiation. These studies show that activation of mitogen-activated protein kinase pathways by G-protein-coupled Receptors and tyrosine kinase Receptors proceed through distinct molecular pathways in PC12 cells, and support an obligatory role for Src activation in mitogenic responses to alpha(1A)-ARs in these cells.
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Activation of tyrosine kinases by α1A-Adrenergic and growth factor Receptors in transfected PC12 cells
Biochemical Journal, 1999Co-Authors: Hongying Zhong, Kenneth P. MinnemanAbstract:We compared the role of tyrosine kinases in alpha(1A)-Adrenergic Receptor (AR) and growth factor Receptor stimulation of mitogen-activated protein kinase pathways in PC12 cells. Norepinephrine (NE) (noradrenaline), epidermal growth factor (EGF) and nerve growth factor (NGF) caused different patterns of tyrosine phosphorylation in PC12 cells stably expressing alpha(1A)-ARs. NE increased tyrosine phosphorylation of focal adhesion-related kinase Pyk2 and a 70 kDa protein, probably paxillin, whereas EGF strongly stimulated tyrosine phosphorylation of the EGF Receptor and cytokine-activated kinase Jak2. The EGF Receptor inhibitor AG1478 inhibited activation of extracellular signal-regulated kinases (ERKs) by EGF but not by NE. EGF and NGF strongly activated tyrosine phosphorylation of Shc and caused association of Src-homology collagen (Shc) with growth-factor-Receptor-bound protein 2 (Grb2); however, neither NE nor UTP caused substantial activation of the Shc/Grb2 pathway. NE, UTP, EGF and NGF all increased tyrosine phosphorylation of Src, and this was inhibited by the Src inhibitor PP2. However, PP2 inhibited ERK activation in response to NE and UTP, but not in response to EGF or NGF. PP2 also completely blocked NE-induced PC12 cell differentiation, but had no measurable effect on NGF-induced differentiation. These studies show that activation of mitogen-activated protein kinase pathways by G-protein-coupled Receptors and tyrosine kinase Receptors proceed through distinct molecular pathways in PC12 cells, and support an obligatory role for Src activation in mitogenic responses to alpha(1A)-ARs in these cells.
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No role for Ca++ or protein kinase C in Alpha-1A Adrenergic Receptor activation of mitogen-activated protein kinase pathways in transfected PC12 cells.
Molecular pharmacology, 1999Co-Authors: Alf Berts, Hongying Zhong, Kenneth P. MinnemanAbstract:We studied the role of Ca++ and protein kinase C (PKC) in Alpha-1A Adrenergic Receptor (AR)-mediated activation of mitogen-activated protein kinase pathways in PC12 cells. In PC12 cells stably transfected with the human Alpha-1A AR, norepinephrine (NE) strongly activated both extracellular signal regulated kinases (ERKs) and c-jun-NH2-terminal kinases (JNK). Ten nanomolar thapsigargin (TG) increased cytoplasmic Ca++ at least as much as NE but did not activate ERKs or JNK. Higher concentrations of TG caused a small activation of ERKs but not JNK. Emptying [Ca++]i stores by pretreatment with TG prevented the NE-stimulated increase in [Ca++]i but not ERK or JNK activation. The Ca++ chelator bis(2-aminophenoxy)ethane-N-N-N'-N'-tetraacetate (BAPTA) dose dependently abolished NE-stimulated Ca++ responses but not ERK or JNK activation. NE increased tyrosine phosphorylation of Pyk2, and this response was neither blocked by BAPTA nor mimicked by TG. The phorbol ester tumor promoting agent (TPA) caused a dose-dependent activation of ERKs that was potentiated by 10 nM TG. TPA caused only a small activation of JNK relative to that caused by NE, which was not affected by TG. The potent PKC inhibitor bisindolylmaleimide I dose dependently inhibited ERK and JNK activation by TPA, but not NE. ATP and UTP activated similar mitogen-activated protein kinase responses through endogenous P2Y2 Receptors, and these responses were not blocked by BAPTA or bisindolylmaleimide I, suggesting that these results may be generalizable to other Gq/11-coupled Receptors. The results suggest that Ca++ release and PKC activation are neither necessary nor sufficient for Alpha-1A AR-mediated activation of mitogenic responses in PC12 cells.
Philip M Swigart - One of the best experts on this subject based on the ideXlab platform.
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coupling to gq signaling is required for cardioprotection by an alpha 1a Adrenergic Receptor agonist
Circulation Research, 2019Co-Authors: Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Taylor Ismaili, Anaha Raghunathan, Sunil Sahdeo, Jonathan M Blevitt, Marcos E MillaAbstract:Rationale: Gq signaling in cardiac myocytes is classically considered toxic. Targeting Gq directly to test this is problematic, because cardiac myocytes have many Gq-coupled Receptors. Objective: T...
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an alpha 1a Adrenergic Receptor agonist prevents acute doxorubicin cardiomyopathy in male mice
PLOS ONE, 2017Co-Authors: Baterdene Myagmar, Megan D Montgomery, Philip M Swigart, Trevor Chan, Rajesh DashAbstract:Alpha-1 Adrenergic Receptors mediate adaptive effects in the heart and cardiac myocytes, and a myocyte survival pathway involving the Alpha-1A Receptor subtype and ERK activation exists in vitro. However, data in vivo are limited. Here we tested A61603 (N-[5-(4,5-dihydro-1H-imidazol-2-yl)-2-hydroxy-5,6,7,8-tetrahydronaphthalen-1-yl]methanesulfonamide), a selective imidazoline agonist for the Alpha-1A. A61603 was the most potent alpha-1-agonist in activating ERK in neonatal rat ventricular myocytes. A61603 activated ERK in adult mouse ventricular myocytes and protected the cells from death caused by the anthracycline doxorubicin. A low dose of A61603 (10 ng/kg/d) activated ERK in the mouse heart in vivo, but did not change blood pressure. In male mice, concurrent subcutaneous A61603 infusion at 10 ng/kg/d for 7 days after a single intraperitoneal dose of doxorubicin (25 mg/kg) increased survival, improved cardiac function, heart rate, and cardiac output by echocardiography, and reduced cardiac cell necrosis and apoptosis and myocardial fibrosis. All protective effects were lost in Alpha-1A-knockout mice. In female mice, doxorubicin at doses higher than in males (35-40 mg/kg) caused less cardiac toxicity than in males. We conclude that the Alpha-1A-selective agonist A61603, via the Alpha-1A Adrenergic Receptor, prevents doxorubicin cardiomyopathy in male mice, supporting the theory that Alpha-1A Adrenergic Receptor agonists have potential as novel heart failure therapies.
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The Alpha-1A Adrenergic Receptor in the Rabbit Heart
PloS one, 2016Co-Authors: R. Croft Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Paul C SimpsonAbstract:The Alpha-1A-Adrenergic Receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the Alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the Alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with
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the alpha 1a Adrenergic Receptor in the rabbit heart
PLOS ONE, 2016Co-Authors: Croft R Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Philip M Swigart, Anthony J BakerAbstract:The Alpha-1A-Adrenergic Receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the Alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the Alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with <1% Alpha-1A and alpha-1D, whereas Alpha-1A mRNA was over 50% of total in brain and liver. Saturation radioligand binding identified ~4 fmol total alpha-1-ARs per mg myocardial protein, with 17% Alpha-1A by competition with the selective antagonist 5-methylurapidil. The alpha-1D was not detected by competition with BMY-7378, indicating that 83% of alpha-1-ARs were alpha-1B. In isolated left ventricle and right ventricle, the selective Alpha-1A agonist A61603 stimulated a negative inotropic effect, versus a positive inotropic effect with the nonselective alpha-1-agonist phenylephrine and the beta-agonist isoproterenol. Blood pressure assay in conscious rabbits using an indwelling aortic telemeter showed that A61603 by bolus intravenous dosing increased mean arterial pressure by 20 mm Hg at 0.14 μg/kg, 10-fold lower than norepinephrine, and chronic A61603 infusion by iPRECIO programmable micro Infusion pump did not increase BP at 22 μg/kg/d. A myocardial slice model useful in human myocardium and an anthracycline cardiotoxicity model useful in mouse were both problematic in rabbit. We conclude that Alpha-1A mRNA is very low in rabbit heart, but the Receptor is present by binding and mediates a negative inotropic response. Expression and function of the Alpha-1A in rabbit heart differ from mouse and human, but the vasopressor response is similar to mouse.
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a myocardial slice culture model reveals alpha 1a Adrenergic Receptor signaling in the human heart
JACC: Basic to Translational Science, 2016Co-Authors: Croft R Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Megan D Montgomery, Philip M Swigart, Teresa De Marco, Anthony J Baker, Paul C SimpsonAbstract:Translation of preclinical findings could benefit from a simple, reproducible, high throughput human model to study myocardial signaling. Alpha-1A-Adrenergic Receptors (ARs) are expressed at very low levels in the human heart, and it is unknown if they function.To develop a high throughput human myocardial slice culture model, and to test the hypothesis that Alpha-1A- ARs are functional in the human heart.Cores of LV free wall 8 mm diameter were taken from 52 hearts (18 failing and 34 nonfailing). Slices 250 μm thick were cut with a Krumdieck apparatus and cultured using a rotating incubation unit.About 60 slices were cut from each LV core, and a typical study could use 96 slices. Myocyte morphology was maintained, and diffusion into the slice center was rapid. Slice viability was stable for at least 3 days in culture by ATP and MTT assays. The beta-AR agonist isoproterenol stimulated phospholamban phosphorylation, and the Alpha-1A-AR agonist A61603 stimulated ERK phosphorylation, with nanomolar EC50 values in slices from both failing and nonfailing hearts. Strips cut from the slices were used to quantify activation of contraction by isoproterenol, A61603, and phenylephrine. The slices supported transduction by adenovirus.We have developed a simple, high throughput LV myocardial slice culture model to study signaling in the human heart. This model can be useful for translational studies, and we show for the first time that the Alpha-1A-AR is functional in signaling and contraction in the human heart.
Anthony J Baker - One of the best experts on this subject based on the ideXlab platform.
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coupling to gq signaling is required for cardioprotection by an alpha 1a Adrenergic Receptor agonist
Circulation Research, 2019Co-Authors: Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Taylor Ismaili, Anaha Raghunathan, Sunil Sahdeo, Jonathan M Blevitt, Marcos E MillaAbstract:Rationale: Gq signaling in cardiac myocytes is classically considered toxic. Targeting Gq directly to test this is problematic, because cardiac myocytes have many Gq-coupled Receptors. Objective: T...
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the alpha 1a Adrenergic Receptor in the rabbit heart
PLOS ONE, 2016Co-Authors: Croft R Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Philip M Swigart, Anthony J BakerAbstract:The Alpha-1A-Adrenergic Receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the Alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the Alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with <1% Alpha-1A and alpha-1D, whereas Alpha-1A mRNA was over 50% of total in brain and liver. Saturation radioligand binding identified ~4 fmol total alpha-1-ARs per mg myocardial protein, with 17% Alpha-1A by competition with the selective antagonist 5-methylurapidil. The alpha-1D was not detected by competition with BMY-7378, indicating that 83% of alpha-1-ARs were alpha-1B. In isolated left ventricle and right ventricle, the selective Alpha-1A agonist A61603 stimulated a negative inotropic effect, versus a positive inotropic effect with the nonselective alpha-1-agonist phenylephrine and the beta-agonist isoproterenol. Blood pressure assay in conscious rabbits using an indwelling aortic telemeter showed that A61603 by bolus intravenous dosing increased mean arterial pressure by 20 mm Hg at 0.14 μg/kg, 10-fold lower than norepinephrine, and chronic A61603 infusion by iPRECIO programmable micro Infusion pump did not increase BP at 22 μg/kg/d. A myocardial slice model useful in human myocardium and an anthracycline cardiotoxicity model useful in mouse were both problematic in rabbit. We conclude that Alpha-1A mRNA is very low in rabbit heart, but the Receptor is present by binding and mediates a negative inotropic response. Expression and function of the Alpha-1A in rabbit heart differ from mouse and human, but the vasopressor response is similar to mouse.
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The Alpha-1A Adrenergic Receptor in the Rabbit Heart
PloS one, 2016Co-Authors: R. Croft Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Paul C SimpsonAbstract:The Alpha-1A-Adrenergic Receptor (AR) subtype is associated with cardioprotective signaling in the mouse and human heart. The rabbit is useful for cardiac disease modeling, but data on the Alpha-1A in the rabbit heart are limited. Our objective was to test for expression and function of the Alpha-1A in rabbit heart. By quantitative real-time reverse transcription PCR (qPCR) on mRNA from ventricular myocardium of adult male New Zealand White rabbits, the alpha-1B was 99% of total alpha-1-AR mRNA, with
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a myocardial slice culture model reveals alpha 1a Adrenergic Receptor signaling in the human heart
JACC: Basic to Translational Science, 2016Co-Authors: Croft R Thomas, Abhishek Singh, Patrick M Cowley, Baterdene Myagmar, Megan D Montgomery, Philip M Swigart, Teresa De Marco, Anthony J Baker, Paul C SimpsonAbstract:Translation of preclinical findings could benefit from a simple, reproducible, high throughput human model to study myocardial signaling. Alpha-1A-Adrenergic Receptors (ARs) are expressed at very low levels in the human heart, and it is unknown if they function.To develop a high throughput human myocardial slice culture model, and to test the hypothesis that Alpha-1A- ARs are functional in the human heart.Cores of LV free wall 8 mm diameter were taken from 52 hearts (18 failing and 34 nonfailing). Slices 250 μm thick were cut with a Krumdieck apparatus and cultured using a rotating incubation unit.About 60 slices were cut from each LV core, and a typical study could use 96 slices. Myocyte morphology was maintained, and diffusion into the slice center was rapid. Slice viability was stable for at least 3 days in culture by ATP and MTT assays. The beta-AR agonist isoproterenol stimulated phospholamban phosphorylation, and the Alpha-1A-AR agonist A61603 stimulated ERK phosphorylation, with nanomolar EC50 values in slices from both failing and nonfailing hearts. Strips cut from the slices were used to quantify activation of contraction by isoproterenol, A61603, and phenylephrine. The slices supported transduction by adenovirus.We have developed a simple, high throughput LV myocardial slice culture model to study signaling in the human heart. This model can be useful for translational studies, and we show for the first time that the Alpha-1A-AR is functional in signaling and contraction in the human heart.
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abstract 20575 an alpha 1a Adrenergic Receptor agonist prevents and treats heart failure
Circulation, 2014Co-Authors: Megan D Montgomery, Baterdene Myagmar, Philip M Swigart, Anthony J Baker, Trevor Chan, Raj Dash, Paul C SimpsonAbstract:INTRODUCTION: The neurohormonal hypothesis that sympathetic activation in heart failure (HF) is toxic to the heart led to class I recommended drugs. However, contrary data suggest that sympathetic blockade in HF has limits, such as the negative effects of alpha-1-Adrenergic Receptor (a1-AR) blockade in humans in ALLHAT and V-HeFT. Conversely, a1-agonists protect myocytes and hearts of multiple species in multiple models through pleiotropic mechanisms, but this is untested in HF in vivo. HYPOTHESIS: We hypothesized that a1-AR agonism can treat HF in vivo. METHODS: We screened drugs in neonatal rat and adult mouse ventricular myocytes (NRVM, AMVM), measured telemetry blood pressure (BP), and did subcutaneous infusion in mice with HF from cardiotoxin (doxorubicin, DOX) and pressure overload (TAC). RESULTS: In NRVMs, the a1A agonist A61603 (A6) was the most efficacious and potent of 10 a1 agonists in ERK activation (EC50 6±1 nM, Emax 22±7) and protein synthesis (EC50 10±1 nM, Emax 1.7±0.1), and EC50s matched a1A binding affinity. In AMVMs, A6 activated ERK (EC50 39±5 nM) and protected against DOX (EC50 15±8 nM, Emax 35±6), an effect lost in the a1A KO. In isolated hearts, A6 activated ERK target genes. A6 10 ng/kg/d infused sc for 7 days had no effect on BP, but increased cardiac pERK (EC50 0.1±0.1 μg/kg/d). With DOX, A6 10 ng/kg/d started at the same time enhanced survival (A6+DOX 84%, n=21; Veh+DOX 34%, n=49). A6 also preserved function (A6 FS 61±2% vs. Veh 49±3%), and reduced serum CK (571±67 vs. 1204±98), TUNEL staining (0.5±0.1 vs. 1.3±0.2), and Sirius Red staining (25±1 vs. 32±1) (n=3-5). A6 effects on survival and FS after DOX were lost in the a1A KO. With TAC (gradient 109 mmHg), FS fell over 2 weeks to 40±1%. A6 from weeks 2 to 4 increased FS (to 51±2%, n=30), while FS remained low with Veh (39±2%, n=24). A6 after TAC did not change heart or myocytes size, but did increase pERK and bMyHC, and reduced cardiac troponin I (A6 5±2 vs. 11±2), cleaved caspase 3 (77±7% of Veh), collagens I and III (46±5% and 56±8% of Veh), and Sirius Red staining (5±4% vs. 9±8%) (n=3-22). CONCLUSIONS: The high affinity a1A-AR agonist A61603, at a low dose that does not change BP, prevents cell death and fibrosis and improves function and mortality in two mouse models of HF. a1A-AR agonists might be potential HF therapies.