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Fazoil Inoyatovich Ataullakhanov - One of the best experts on this subject based on the ideXlab platform.
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mathematical analysis of human red blood cell Volume regulation with regard to the elastic effect of the Erythrocyte shell on metabolic processes
Biochemistry (moscow) Supplement Series A: Membrane and Cell Biology, 2013Co-Authors: N V Kalyagina, M. V. Martinov, Fazoil Inoyatovich AtaullakhanovAbstract:The mathematical model of the regulation of ion exchange and human Erythrocyte Volume is extended with a biomechanical model of the Erythrocyte shell. This model was used to analyze the influence of elastic properties of the Erythrocyte shell on Erythrocyte Volume in the experiments, where the Volume of Erythrocytes increased due to the formation of ion channels in the membrane after the treatment with amphotericin B and in case of placing red blood cells in a hypo-osmotic medium. During red blood cell deformation at a constant surface area up to sphericity, the influence of mechanical properties of the shell on Volume regulation was shown to be negligible compared to the influence of ion exchange. Further osmotic swelling of red blood cells followed by the increase in their surface area is determined by tensile stiffness of the shell. The high value of tensile stiffness inherent to the Erythrocyte shell is constraint for its Volume change and also affects ion exchange.
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Anion permeability and Erythrocyte swelling
Bioelectrochemistry, 2000Co-Authors: V. M. Vitvitsky, S. V. Komarova, M. V. Martinov, E. V. Frolova, Fazoil Inoyatovich AtaullakhanovAbstract:Abstract Permeability of cell membranes to cations may increase as a result of membrane oxidation or in certain pathologies. We studied the effects of nonselective increases in cell membrane permeability to univalent cations on the Volume of Erythrocytes incubated in phosphate-buffered saline (PBS) using amphotericin B (5–10 mg/l suspension) or gramicidin D (10–100 μg/l suspension) as the membrane permeabilizing agents. Both antibiotics caused K + to leak, Na + to accumulate intracellularly, and cell Volume to increase. The interval needed to reach the equilibrium between the intracellular and extracellular ion concentrations ranged from 30 min to several hours, depending on the antibiotic concentration. In spite of a rapid disappearance of cation transmembrane gradients, cell Volume increased relatively slow. Even 24 h after the membrane permeability was changed, the Volume of most Erythrocytes did not increase to the lytic values (about 1.6 times the normal Volume). The slow increase in Erythrocyte Volume was accounted for by slow changes in the transmembrane Cl − gradient. 4,4′-Diisothiocyanatostilbene-2,2′-disulfonic acid (DIDS), a specific inhibitor of anion transport, while producing no effect on the transmembrane Na + and K + fluxes induced by the antibiotics, significantly inhibited the decrease in the transmembrane Cl − gradient and the increase in Erythrocyte Volume. Analysis of these data by means of mathematical modeling showed that it failed to satisfactorily describe the experimental kinetics of Erythrocyte swelling in response to increases in the membrane permeability to univalent cations if its permeability to Cl − was set to be constant. The satisfactory description of this kinetics could be achieved by assuming that the membrane permeability to anions decreased with increasing Erythrocyte Volume. The results obtained demonstrate that transmembrane anion transport may be considered to be a component of the mechanism responsible for the Erythrocyte Volume stabilization, because a significant decrease in the swelling rate allows the Erythrocytes with damaged membranes to activate a relatively slow (metabolic) mechanisms of cell Volume stabilization and/or repair their damaged membranes.
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Anion permeability and Erythrocyte swelling
Bioelectrochemistry, 2000Co-Authors: V. M. Vitvitsky, S. V. Komarova, M. V. Martinov, E. V. Frolova, Fazoil Inoyatovich AtaullakhanovAbstract:Permeability of cell membranes to cations may increase as a result of membrane oxidation or in certain pathologies. We studied the effects of nonselective increases in cell membrane permeability to univalent cations on the Volume of Erythrocytes incubated in phosphate-buffered saline (PBS) using amphotericin B (5-10 mg/l suspension) or gramicidin D (10-100 μg/l suspension) as the membrane permeabilizing agents. Both antibiotics caused K+to leak, Na+to accumulate intracellularly, and cell Volume to increase. The interval needed to reach the equilibrium between the intracellular and extracellular ion concentrations ranged from 30 min to several hours, depending on the antibiotic concentration. In spite of a rapid disappearance of cation transmembrane gradients, cell Volume increased relatively slow. Even 24 h after the membrane permeability was changed, the Volume of most Erythrocytes did not increase to the lytic values (about 1.6 times the normal Volume). The slow increase in Erythrocyte Volume was accounted for by slow changes in the transmembrane Cl-gradient. 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), a specific inhibitor of anion transport, while producing no effect on the transmembrane Na+and K+fluxes induced by the antibiotics, significantly inhibited the decrease in the transmembrane Cl-gradient and the increase in Erythrocyte Volume. Analysis of these data by means of mathematical modeling showed that it failed to satisfactorily describe the experimental kinetics of Erythrocyte swelling in response to increases in the membrane permeability to univalent cations if its permeability to Cl-was set to be constant. The satisfactory description of this kinetics could be achieved by assuming that the membrane permeability to anions decreased with increasing Erythrocyte Volume. The results obtained demonstrate that transmembrane anion transport may be considered to be a component of the mechanism responsible for the Erythrocyte Volume stabilization, because a significant decrease in the swelling rate allows the Erythrocytes with damaged membranes to activate a relatively slow (metabolic) mechanisms of cell Volume stabilization and/or repair their damaged membranes. © 2000 Elsevier Science S.A.
Alicia Rivera - One of the best experts on this subject based on the ideXlab platform.
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endothelial specific knockdown of caveolin 1 lowers circulating protein disulfide isomerase levels and is associated with changes in Erythrocyte Volume homeostasis
Blood, 2013Co-Authors: Jose R Romero, Enrique D Machadofiallo, Arelys Ramosrivera, Gregory N Prado, Luminita H Pojoga, Alicia RiveraAbstract:We have recently reported that Endothelin-1 (ET1), a potent vasoconstrictor peptide, is implicated in the pathophysiology of Sickle Cell Disease (SCD) via increased circulating Protein Disulfide Isomerase (PDI) activity (Prado, 2013 FASEB J ). PDI is a multifunctional enzyme of the thioredoxin superfamily that mediates redox modifications, catalyzes disulfide interchange reactions in the plasma membrane, regulates KCNN4 channel and Erythrocyte Volume and is up-regulated under hypoxic conditions as commonly observed in SCD. In Erythrocytes, ET1 stimulates PDI activity via activation of ET1 receptor B (ETRB). However, the precise mechanisms by which ET1 leads to increases in PDI are not entirely clear. There is evidence that activation of endothelial cells leads to increased PDI secretion and that ETRBs form a complex with caveolin-1 (CAV1) within caveolae to mediate ET1’s cellular effects. We tested the hypothesis that reduction of CAV1 would alter PDI secretion. We studied the in vivo effects of endothelial-specific CAV1 knockdown on circulating PDI activity in mice. We optimized conditions to measure circulating PDI using fluorescently labeled GSSG conversion to GSH. We now report that circulating plasma PDI levels were significantly decreased in CAV1 knockdown mice when compared to wild-type littermates (WT) (7.44±0.70 vs 10.93±2.66, n=7, P <0.05). In addition and consistent with our report showing a role for PDI in Erythrocyte Volume regulation, we also observed lower cell hemoglobin concentration mean (CHCM) and hemoglobin distribution width (HDW) that was associated with increased Erythrocyte and reticulocyte mean cell Volume (MCV) in blood from CAV1 knockdown mice when compared to WT (n=13 and n=19, respectively, P <0.005). We then isolated early cultures of mouse aortic endothelial cells (MAEC) from these mice and measured PDI activity following 24 hrs of incubation in 0.4% fetal bovine serum. Our results show that MAEC from CAV1 knockdown mice had lower PDI secretion when compared to cells from WT mice (99.4±16 vs 129.9±35, n=5, P <0.03). We then studied the effects of ET1 on PDI secretion from human endothelial cells. We detected PDI and ETRB by western blot analyses in membranes from the human endothelial cell line, EA.hy926 (EA). We observed that incubation of EA cells for 60 mins with 10-7 M ET1 was associated with increased extracellular PDI activity (15.97±7.22 to 34.07±8.89 [RFU/mg protein], n=3, P <0.011) that was sensitive to preincubation with BQ788, a specific ETRB receptor antagonist (15.97±7.22 to 7.97±3.25 (RFU/mg protein), n=3, P <0.02). Similar increases in PDI were observed when cells were treated with the specific ETRB agonist, IRL1620 (1143±137 to 1593 207 RFU/mg protein). In addition, PDI siRNA knockdown was associated with reduced ET1-stimulated PDI activity when compared to scrambled siRNA transfected cells (1731±147 to 757±141 RFU, n=2). We then tested the effects of methyl-β-cyclodextrin to disrupt caveolae in these cells and observed a blunted IRL1620–stimulated PDI response (288±40 to 171±14 RFU/mg protein, n=3, P <0.025). We also characterized the effects of ET1 on PDI expression in EA cells, using quantitative RT-PCR with ABI TaqMan probes and β-actin as an endogenous control and observed that stimulation of EA cells with 10-8 M ET1 for 4 hr was associated with increased PDI mRNA expression levels that were 1.89 fold greater than vehicle treated cells (n=6, P <0.04). Thus our results provide evidence for a heretofore unrecognized role of endothelial specific CAV1 in Erythrocyte Volume and circulating PDI levels. Supported by NIH R01HL090632 (AR) and R01HL104032 (LHP). Disclosures: No relevant conflicts of interest to declare.
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Endothelial-Specific Knockdown Of Caveolin-1 Lowers Circulating Protein Disulfide Isomerase Levels and Is Associated With Changes In Erythrocyte Volume Homeostasis
Blood, 2013Co-Authors: Jose R Romero, Gregory N Prado, Luminita H Pojoga, Enrique D. Machado-fiallo, Arelys Ramos-rivera, Alicia RiveraAbstract:We have recently reported that Endothelin-1 (ET1), a potent vasoconstrictor peptide, is implicated in the pathophysiology of Sickle Cell Disease (SCD) via increased circulating Protein Disulfide Isomerase (PDI) activity (Prado, 2013 FASEB J ). PDI is a multifunctional enzyme of the thioredoxin superfamily that mediates redox modifications, catalyzes disulfide interchange reactions in the plasma membrane, regulates KCNN4 channel and Erythrocyte Volume and is up-regulated under hypoxic conditions as commonly observed in SCD. In Erythrocytes, ET1 stimulates PDI activity via activation of ET1 receptor B (ETRB). However, the precise mechanisms by which ET1 leads to increases in PDI are not entirely clear. There is evidence that activation of endothelial cells leads to increased PDI secretion and that ETRBs form a complex with caveolin-1 (CAV1) within caveolae to mediate ET1’s cellular effects. We tested the hypothesis that reduction of CAV1 would alter PDI secretion. We studied the in vivo effects of endothelial-specific CAV1 knockdown on circulating PDI activity in mice. We optimized conditions to measure circulating PDI using fluorescently labeled GSSG conversion to GSH. We now report that circulating plasma PDI levels were significantly decreased in CAV1 knockdown mice when compared to wild-type littermates (WT) (7.44±0.70 vs 10.93±2.66, n=7, P
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regulation of Erythrocyte Volume by cell surface associated protein disulfide isomerase
Blood, 2007Co-Authors: Jose R Romero, Manuel D Bicho, Linchien Pong, Joel Greenbowe, Alicia RiveraAbstract:Acute and chronic clinical manifestations of sickle cell disease (SCD) are based on vaso-occlusion and impaired blood flow. Dense Erythrocytes are believed to be important contributors to the vaso-occlusive manifestations of SCD. However, the physiological regulation of Erythrocyte hydration status in SCD is not entirely clear. The Gardos channel and K/Cl cotransport are major contributors to sickle Erythrocyte dehydration. Protein disulfide isomerase (PDI) on the cell surface catalyzes disulfide formation, causes redox modifications and has been observed to be up-regulated under hypoxic conditions. We now report the detection of PDI in red cells. Western blot analysis revealed a prominent band, migrating at 55 kDa, in ghost preparation from both sickle and normal Erythrocytes. To evaluate the role of PDI in Gardos channel activation, we measured charybdotoxin-sensitive K+ influx in the presence of bacitracin, a well-known blocker of PDI activity. When sickle Erythrocytes are exposed to bacitracin, Gardos channel activity is significantly reduced (1.4 ±0.2 to 0.8± 0.05 mmol/L cell x min, n=6, P<0.01). We also observed that Gardos channel activity was attenuated by 0.25 mM bacitracin and was maximally inhibited by 3 mM in sickle and normal Erythrocytes. Similar results were observed with phenyl arsine oxide and acetyl-thyroxin, two other well-known inhibitors of cell surface PDI activity. We then studied the effects of PDI inhibition on red cell density profiles of sickle and normal human red cells. Analysis of the baseline density profile indicates that Erythrocytes have a median density of 1.10 g/mL. This value significantly increased to 1.125 g/mL (n=2) after 3 h of oxygenation/de-oxygenation cycles. However, in the presence of 3 mM bacitracin, the cellular density profile markedly shifted to the left (1.098 g/mL) following deoxygenation/oxygenation. We also investigated the reductive capacity of freshly isolated human Erythrocytes by the ferrocyanide-production method. The reductive capacity of normal Hb A red cells was significantly lower than in Hb S containing cells (2.8 ± 1.1 vs 5.1 ± 1.3 mmol/L cell x h, n=18, p<0.0001). Similar results were observed in Santillies and NYKO1, two transgenic mouse models of sickle cell disease, when compared to C57 mice. These results strongly implicate cell surface associated PDI in cellular dehydration and formation of dense sickle Erythrocytes by activating K+ efflux via the Gardos channel and suggest that aberrant regulation of PDI activity and/or its expression may contribute to the pathophysiology of Sickle Cell Disease.
Michael N Sawka - One of the best experts on this subject based on the ideXlab platform.
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altitude acclimatization and blood Volume effects of exogenous Erythrocyte Volume expansion
Journal of Applied Physiology, 1996Co-Authors: Michael N Sawka, Andrew J Young, Paul B Rock, Timothy Lyons, Robert Boushel, B J Freund, S R Muza, A Cymerman, R C Dennis, K B PandolfAbstract:We studied sea-level residents during 13 days of altitude acclimatization to determine 1) altitude acclimatization effects on Erythrocyte Volume and plasma Volume, 2) if exogenous Erythrocyte volum...
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Erythrocyte plasma and blood Volume of healthy young men
Medicine and Science in Sports and Exercise, 1992Co-Authors: Michael N Sawka, Andrew J Young, R C Dennis, K B Pandolf, C. R. ValeriAbstract:ABSTRACT: SAWKA, M. N., A. J. YOUNG, K. B. PANDOLF, R. C. DENNIS, and C. R. VALERI. Erythrocyte, plasma, and blood Volume of healthy young men. Med. Sci. Sports Exerc., Vol. 24, No. 4, pp. 447–453, 1992. Insufficient data are readily available concerning the vascular fluid Volumes of healthy young men. The primary purpose of this study was to develop a normative database for the Erythrocyte Volume, plasma Volume, and blood Volume of healthy young men. The secondary purposes were to relate these vascular fluid Volumes to the person's body size and physical fitness level and to develop equations that enable their prediction. Fifty-one male soldiers with a mean age of 22 (range 18–35) yr and with a mean maximal aerobic power of 53 (range 42–65) ml O2 · kg-1· min-1 had their lean body mass and vascular fluid Volumes measured. Erythrocyte Volume was measured by 51Cr, and plasma Volume was measured by 125I. The findings concerning the Erythrocyte Volume, plasma Volume, and blood Volume of these young men are summarized as follows: 1) these vascular fluid Volumes are accurately predicted from several indices of body size; 2) lean body mass is the anthropometric index that is most closely correlated to these vascular fluid Volumes; 3) the Erythrocyte Volumes for a given body surface area are lower, particularly for large individuals, than values previously reported in surveys of undefined populations; 4) aerobic fitness is generally not related to vascular Volumes; and 5) F-cell ratio is not related to aerobic fitness.
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Erythrocyte, Plasma and Blood Volume of Healthy Young Men: Relationships to Body Size and Aerobic Fitness.
1990Co-Authors: Michael N Sawka, Andrew J Young, R C Dennis, Kent B. Pandoif, C. R. ValeriAbstract:Abstract : The primary pprpose of this study was to develop a nounative database for the Erythrocyte Volume, pla%na Volume and blood Volume of healthy young nen. The secondary purposes were to relate these vascular fluid Volumes to the person's body size and physical fitness level and to develop regression equations which enable their accurate prediction. Fifty-one male soldiers with a inean age of 22 (range 18 to 35) years and with a maximal aerobic power of 53 (range 42 to 65) ml 02kg -1.min-1) had their lean body mass and vascular fluid Volumes measured. Erythrocyte Volume was measured by 5ICr for all subjects; plasma Volume was measured by 1251 for forty-three subjects and calculated (assumed F-cell of 0.89) from the Erythrocyte Volume and venous hematocrit for eight subjects. The findings concerning the Erythrocyte Volume, plasma Volume and blood Volume of young men are summarized as follows: 1) these vascular fluid Volumes are accurately predicted from several indices of body size; 2) lean body mass is the anthropanetric ind% which is most closely correlated to these vascular fluid Volumes; 3) aerobic fitness does not influence these vascular fluid Volumes in individuals not recently participating in intense physical training; and 4) F-cell ratio is not related to aerobic fitness.
Jose R Romero - One of the best experts on this subject based on the ideXlab platform.
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endothelial specific knockdown of caveolin 1 lowers circulating protein disulfide isomerase levels and is associated with changes in Erythrocyte Volume homeostasis
Blood, 2013Co-Authors: Jose R Romero, Enrique D Machadofiallo, Arelys Ramosrivera, Gregory N Prado, Luminita H Pojoga, Alicia RiveraAbstract:We have recently reported that Endothelin-1 (ET1), a potent vasoconstrictor peptide, is implicated in the pathophysiology of Sickle Cell Disease (SCD) via increased circulating Protein Disulfide Isomerase (PDI) activity (Prado, 2013 FASEB J ). PDI is a multifunctional enzyme of the thioredoxin superfamily that mediates redox modifications, catalyzes disulfide interchange reactions in the plasma membrane, regulates KCNN4 channel and Erythrocyte Volume and is up-regulated under hypoxic conditions as commonly observed in SCD. In Erythrocytes, ET1 stimulates PDI activity via activation of ET1 receptor B (ETRB). However, the precise mechanisms by which ET1 leads to increases in PDI are not entirely clear. There is evidence that activation of endothelial cells leads to increased PDI secretion and that ETRBs form a complex with caveolin-1 (CAV1) within caveolae to mediate ET1’s cellular effects. We tested the hypothesis that reduction of CAV1 would alter PDI secretion. We studied the in vivo effects of endothelial-specific CAV1 knockdown on circulating PDI activity in mice. We optimized conditions to measure circulating PDI using fluorescently labeled GSSG conversion to GSH. We now report that circulating plasma PDI levels were significantly decreased in CAV1 knockdown mice when compared to wild-type littermates (WT) (7.44±0.70 vs 10.93±2.66, n=7, P <0.05). In addition and consistent with our report showing a role for PDI in Erythrocyte Volume regulation, we also observed lower cell hemoglobin concentration mean (CHCM) and hemoglobin distribution width (HDW) that was associated with increased Erythrocyte and reticulocyte mean cell Volume (MCV) in blood from CAV1 knockdown mice when compared to WT (n=13 and n=19, respectively, P <0.005). We then isolated early cultures of mouse aortic endothelial cells (MAEC) from these mice and measured PDI activity following 24 hrs of incubation in 0.4% fetal bovine serum. Our results show that MAEC from CAV1 knockdown mice had lower PDI secretion when compared to cells from WT mice (99.4±16 vs 129.9±35, n=5, P <0.03). We then studied the effects of ET1 on PDI secretion from human endothelial cells. We detected PDI and ETRB by western blot analyses in membranes from the human endothelial cell line, EA.hy926 (EA). We observed that incubation of EA cells for 60 mins with 10-7 M ET1 was associated with increased extracellular PDI activity (15.97±7.22 to 34.07±8.89 [RFU/mg protein], n=3, P <0.011) that was sensitive to preincubation with BQ788, a specific ETRB receptor antagonist (15.97±7.22 to 7.97±3.25 (RFU/mg protein), n=3, P <0.02). Similar increases in PDI were observed when cells were treated with the specific ETRB agonist, IRL1620 (1143±137 to 1593 207 RFU/mg protein). In addition, PDI siRNA knockdown was associated with reduced ET1-stimulated PDI activity when compared to scrambled siRNA transfected cells (1731±147 to 757±141 RFU, n=2). We then tested the effects of methyl-β-cyclodextrin to disrupt caveolae in these cells and observed a blunted IRL1620–stimulated PDI response (288±40 to 171±14 RFU/mg protein, n=3, P <0.025). We also characterized the effects of ET1 on PDI expression in EA cells, using quantitative RT-PCR with ABI TaqMan probes and β-actin as an endogenous control and observed that stimulation of EA cells with 10-8 M ET1 for 4 hr was associated with increased PDI mRNA expression levels that were 1.89 fold greater than vehicle treated cells (n=6, P <0.04). Thus our results provide evidence for a heretofore unrecognized role of endothelial specific CAV1 in Erythrocyte Volume and circulating PDI levels. Supported by NIH R01HL090632 (AR) and R01HL104032 (LHP). Disclosures: No relevant conflicts of interest to declare.
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Endothelial-Specific Knockdown Of Caveolin-1 Lowers Circulating Protein Disulfide Isomerase Levels and Is Associated With Changes In Erythrocyte Volume Homeostasis
Blood, 2013Co-Authors: Jose R Romero, Gregory N Prado, Luminita H Pojoga, Enrique D. Machado-fiallo, Arelys Ramos-rivera, Alicia RiveraAbstract:We have recently reported that Endothelin-1 (ET1), a potent vasoconstrictor peptide, is implicated in the pathophysiology of Sickle Cell Disease (SCD) via increased circulating Protein Disulfide Isomerase (PDI) activity (Prado, 2013 FASEB J ). PDI is a multifunctional enzyme of the thioredoxin superfamily that mediates redox modifications, catalyzes disulfide interchange reactions in the plasma membrane, regulates KCNN4 channel and Erythrocyte Volume and is up-regulated under hypoxic conditions as commonly observed in SCD. In Erythrocytes, ET1 stimulates PDI activity via activation of ET1 receptor B (ETRB). However, the precise mechanisms by which ET1 leads to increases in PDI are not entirely clear. There is evidence that activation of endothelial cells leads to increased PDI secretion and that ETRBs form a complex with caveolin-1 (CAV1) within caveolae to mediate ET1’s cellular effects. We tested the hypothesis that reduction of CAV1 would alter PDI secretion. We studied the in vivo effects of endothelial-specific CAV1 knockdown on circulating PDI activity in mice. We optimized conditions to measure circulating PDI using fluorescently labeled GSSG conversion to GSH. We now report that circulating plasma PDI levels were significantly decreased in CAV1 knockdown mice when compared to wild-type littermates (WT) (7.44±0.70 vs 10.93±2.66, n=7, P
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regulation of Erythrocyte Volume by cell surface associated protein disulfide isomerase
Blood, 2007Co-Authors: Jose R Romero, Manuel D Bicho, Linchien Pong, Joel Greenbowe, Alicia RiveraAbstract:Acute and chronic clinical manifestations of sickle cell disease (SCD) are based on vaso-occlusion and impaired blood flow. Dense Erythrocytes are believed to be important contributors to the vaso-occlusive manifestations of SCD. However, the physiological regulation of Erythrocyte hydration status in SCD is not entirely clear. The Gardos channel and K/Cl cotransport are major contributors to sickle Erythrocyte dehydration. Protein disulfide isomerase (PDI) on the cell surface catalyzes disulfide formation, causes redox modifications and has been observed to be up-regulated under hypoxic conditions. We now report the detection of PDI in red cells. Western blot analysis revealed a prominent band, migrating at 55 kDa, in ghost preparation from both sickle and normal Erythrocytes. To evaluate the role of PDI in Gardos channel activation, we measured charybdotoxin-sensitive K+ influx in the presence of bacitracin, a well-known blocker of PDI activity. When sickle Erythrocytes are exposed to bacitracin, Gardos channel activity is significantly reduced (1.4 ±0.2 to 0.8± 0.05 mmol/L cell x min, n=6, P<0.01). We also observed that Gardos channel activity was attenuated by 0.25 mM bacitracin and was maximally inhibited by 3 mM in sickle and normal Erythrocytes. Similar results were observed with phenyl arsine oxide and acetyl-thyroxin, two other well-known inhibitors of cell surface PDI activity. We then studied the effects of PDI inhibition on red cell density profiles of sickle and normal human red cells. Analysis of the baseline density profile indicates that Erythrocytes have a median density of 1.10 g/mL. This value significantly increased to 1.125 g/mL (n=2) after 3 h of oxygenation/de-oxygenation cycles. However, in the presence of 3 mM bacitracin, the cellular density profile markedly shifted to the left (1.098 g/mL) following deoxygenation/oxygenation. We also investigated the reductive capacity of freshly isolated human Erythrocytes by the ferrocyanide-production method. The reductive capacity of normal Hb A red cells was significantly lower than in Hb S containing cells (2.8 ± 1.1 vs 5.1 ± 1.3 mmol/L cell x h, n=18, p<0.0001). Similar results were observed in Santillies and NYKO1, two transgenic mouse models of sickle cell disease, when compared to C57 mice. These results strongly implicate cell surface associated PDI in cellular dehydration and formation of dense sickle Erythrocytes by activating K+ efflux via the Gardos channel and suggest that aberrant regulation of PDI activity and/or its expression may contribute to the pathophysiology of Sickle Cell Disease.
K B Pandolf - One of the best experts on this subject based on the ideXlab platform.
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altitude acclimatization and blood Volume effects of exogenous Erythrocyte Volume expansion
Journal of Applied Physiology, 1996Co-Authors: Michael N Sawka, Andrew J Young, Paul B Rock, Timothy Lyons, Robert Boushel, B J Freund, S R Muza, A Cymerman, R C Dennis, K B PandolfAbstract:We studied sea-level residents during 13 days of altitude acclimatization to determine 1) altitude acclimatization effects on Erythrocyte Volume and plasma Volume, 2) if exogenous Erythrocyte volum...
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Erythrocyte plasma and blood Volume of healthy young men
Medicine and Science in Sports and Exercise, 1992Co-Authors: Michael N Sawka, Andrew J Young, R C Dennis, K B Pandolf, C. R. ValeriAbstract:ABSTRACT: SAWKA, M. N., A. J. YOUNG, K. B. PANDOLF, R. C. DENNIS, and C. R. VALERI. Erythrocyte, plasma, and blood Volume of healthy young men. Med. Sci. Sports Exerc., Vol. 24, No. 4, pp. 447–453, 1992. Insufficient data are readily available concerning the vascular fluid Volumes of healthy young men. The primary purpose of this study was to develop a normative database for the Erythrocyte Volume, plasma Volume, and blood Volume of healthy young men. The secondary purposes were to relate these vascular fluid Volumes to the person's body size and physical fitness level and to develop equations that enable their prediction. Fifty-one male soldiers with a mean age of 22 (range 18–35) yr and with a mean maximal aerobic power of 53 (range 42–65) ml O2 · kg-1· min-1 had their lean body mass and vascular fluid Volumes measured. Erythrocyte Volume was measured by 51Cr, and plasma Volume was measured by 125I. The findings concerning the Erythrocyte Volume, plasma Volume, and blood Volume of these young men are summarized as follows: 1) these vascular fluid Volumes are accurately predicted from several indices of body size; 2) lean body mass is the anthropometric index that is most closely correlated to these vascular fluid Volumes; 3) the Erythrocyte Volumes for a given body surface area are lower, particularly for large individuals, than values previously reported in surveys of undefined populations; 4) aerobic fitness is generally not related to vascular Volumes; and 5) F-cell ratio is not related to aerobic fitness.