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Peter M Cala - One of the best experts on this subject based on the ideXlab platform.
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Distinction between K/H Exchange
2013Co-Authors: Kcl Cotransport, Joseph S. Adorante, Peter M CalaAbstract:A B $ T R A (2 T Exposure of Amphiuma red blood cells to millimolar concentrations of N-ethyimaleimide (NEM) resulted in net K loss. In order to determine whether net K loss was conductive or was by electroneutral K/H exchange or KCI cotransport, studies were performed evaluating K flux in terms of the thermodynamic forces to which K flux by the above pathways should couple. The direction and magnitude of the NEM-induced net K flux did not correspond with the direction and magnitude of the forces relevant to K conductance or electroneutral KCI cotransport. Both the magnitude and direction of the NEM-activated K flux responded to the driving force for K/H exchange. We therefore conclude that NEM-induced K loss, like that by osmotically swollen Amphiuma red blood cells, is by an electroneutral K/H exchanger. In addition to the above studies, we evaluated the kinetic behavior of the volume- and NEM-induced K/H exchange flux pathways in media where C! was replaced by SCN, NOs, para-aminohippurate (PAH), or gluconate. The anion replacement studies did not permit a distinction between K/H exchange and KC1 cotransport
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pH Regulatory Na/H Exchange
2013Co-Authors: Red Blood Cells, Peter M Cala, Hector M MaldonadoAbstract:InAmphiuma red blood cells, the Na/H exchanger has been shown to play a central role in the regulation of cell volume following cell shrinkage (Cala, P. M. 1980. Journal of General Physiology. 76:683-708.) The present study was designed to evaluate the existence of pH regulatory Na/H exchange in the Amphiuma red blood cell. The data illustrate that when the intracellular pHi was decreased below the normal value of 7.00, Na/H exchange was activated in proportion to the degree of acidification. Once activated, net Na/H exchange flux persisted until normal intracellular pH (6.9-7.0) was restored, with a half time of = 5 min. These observations established a pHi set point of 7.00 for the pH-activated Na/H exchange of Amphiuma red blood cell. This is in contrast to the behavior of osmotically shrunken Araphiuma red blood cells in which no pHi set point could be demonstrated. That is, when activated by cell shrinkage the Na/H exchange mediated net Na flux persisted until normal volume was restored regardless of pHi. In contrast, when activated by cell acidification, the Na/H exchanger functione
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coordinated control of volume regulatory na h and k h exchange pathways in Amphiuma red blood cells
American Journal of Physiology-cell Physiology, 2010Co-Authors: Alejandro Ortizacevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:The Na+/H+ and K+/H+ exchange pathways of Amphiuma tridactylum red blood cells (RBCs) are quiescent at normal resting cell volume yet are selectively activated in response to cell shrinkage and swe...
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Coordinated control of volume regulatory Na+/H+ and K+/H+ exchange pathways in Amphiuma red blood cells.
American journal of physiology. Cell physiology, 2009Co-Authors: Alejandro Ortiz-acevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:The Na+/H+ and K+/H+ exchange pathways of Amphiuma tridactylum red blood cells (RBCs) are quiescent at normal resting cell volume yet are selectively activated in response to cell shrinkage and swe...
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activation of na h and k h exchange by calyculin a in Amphiuma tridactylum red blood cells implications for the control of volume induced ion flux activity
American Journal of Physiology-cell Physiology, 2008Co-Authors: Alejandro Ortizacevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:Alteration in cell volume of vertebrates results in activation of volume-sensitive ion flux pathways. Fine control of the activity of these pathways enables cells to regulate volume following osmotic perturbation. Protein phosphorylation and dephosphorylation have been reported to play a crucial role in the control of volume-sensitive ion flux pathways. Exposing Amphiuma tridactylu red blood cells (RBCs) to phorbol esters in isotonic medium results in a simultaneous, dose-dependent activation of both Na+/H+ and K+/H+ exchangers. We tested the hypothesis that in Amphiuma RBCs, both shrinkage-induced Na+/H+ exchange and swelling-induced K+/H+ exchange are activated by phosphorylation-dependent reactions. To this end, we assessed the effect of calyculin A, a phosphatase inhibitor, on the activity of the aforementioned exchangers. We found that exposure of Amphiuma RBCs to calyculin-A in isotonic media results in simultaneous, 1–2 orders of magnitude increase in the activity of both K+/H+ and Na+/H+ exchangers. We also demonstrate that, in isotonic media, calyculin A-dependent increases in net Na+ uptake and K+ loss are a direct result of phosphatase inhibition and are not dependent on changes in cell volume. Whereas calyculin A exposure in the absence of volume changes results in stimulation of both the Na+/H+ and K+/H+ exchangers, superimposing cell swelling or shrinkage and calyculin A treatment results in selective activation of K+/H+ or Na+/H+ exchange, respectively. We conclude that kinase-dependent reactions are responsible for Na+/H+ and K+/H+ exchange activity, whereas undefined volume-dependent reactions confer specificity and coordinated control.
Hector M Maldonado - One of the best experts on this subject based on the ideXlab platform.
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pH Regulatory Na/H Exchange
2013Co-Authors: Red Blood Cells, Peter M Cala, Hector M MaldonadoAbstract:InAmphiuma red blood cells, the Na/H exchanger has been shown to play a central role in the regulation of cell volume following cell shrinkage (Cala, P. M. 1980. Journal of General Physiology. 76:683-708.) The present study was designed to evaluate the existence of pH regulatory Na/H exchange in the Amphiuma red blood cell. The data illustrate that when the intracellular pHi was decreased below the normal value of 7.00, Na/H exchange was activated in proportion to the degree of acidification. Once activated, net Na/H exchange flux persisted until normal intracellular pH (6.9-7.0) was restored, with a half time of = 5 min. These observations established a pHi set point of 7.00 for the pH-activated Na/H exchange of Amphiuma red blood cell. This is in contrast to the behavior of osmotically shrunken Araphiuma red blood cells in which no pHi set point could be demonstrated. That is, when activated by cell shrinkage the Na/H exchange mediated net Na flux persisted until normal volume was restored regardless of pHi. In contrast, when activated by cell acidification, the Na/H exchanger functione
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coordinated control of volume regulatory na h and k h exchange pathways in Amphiuma red blood cells
American Journal of Physiology-cell Physiology, 2010Co-Authors: Alejandro Ortizacevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:The Na+/H+ and K+/H+ exchange pathways of Amphiuma tridactylum red blood cells (RBCs) are quiescent at normal resting cell volume yet are selectively activated in response to cell shrinkage and swe...
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Coordinated control of volume regulatory Na+/H+ and K+/H+ exchange pathways in Amphiuma red blood cells.
American journal of physiology. Cell physiology, 2009Co-Authors: Alejandro Ortiz-acevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:The Na+/H+ and K+/H+ exchange pathways of Amphiuma tridactylum red blood cells (RBCs) are quiescent at normal resting cell volume yet are selectively activated in response to cell shrinkage and swe...
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activation of na h and k h exchange by calyculin a in Amphiuma tridactylum red blood cells implications for the control of volume induced ion flux activity
American Journal of Physiology-cell Physiology, 2008Co-Authors: Alejandro Ortizacevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:Alteration in cell volume of vertebrates results in activation of volume-sensitive ion flux pathways. Fine control of the activity of these pathways enables cells to regulate volume following osmotic perturbation. Protein phosphorylation and dephosphorylation have been reported to play a crucial role in the control of volume-sensitive ion flux pathways. Exposing Amphiuma tridactylu red blood cells (RBCs) to phorbol esters in isotonic medium results in a simultaneous, dose-dependent activation of both Na+/H+ and K+/H+ exchangers. We tested the hypothesis that in Amphiuma RBCs, both shrinkage-induced Na+/H+ exchange and swelling-induced K+/H+ exchange are activated by phosphorylation-dependent reactions. To this end, we assessed the effect of calyculin A, a phosphatase inhibitor, on the activity of the aforementioned exchangers. We found that exposure of Amphiuma RBCs to calyculin-A in isotonic media results in simultaneous, 1–2 orders of magnitude increase in the activity of both K+/H+ and Na+/H+ exchangers. We also demonstrate that, in isotonic media, calyculin A-dependent increases in net Na+ uptake and K+ loss are a direct result of phosphatase inhibition and are not dependent on changes in cell volume. Whereas calyculin A exposure in the absence of volume changes results in stimulation of both the Na+/H+ and K+/H+ exchangers, superimposing cell swelling or shrinkage and calyculin A treatment results in selective activation of K+/H+ or Na+/H+ exchange, respectively. We conclude that kinase-dependent reactions are responsible for Na+/H+ and K+/H+ exchange activity, whereas undefined volume-dependent reactions confer specificity and coordinated control.
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Activation of Na+/H+ and K+/H+exchange by calyculin A in Amphiuma tridactylum red blood cells : implications for the control of volume-induced ion flux activity
American journal of physiology. Cell physiology, 2008Co-Authors: Alejandro Ortiz-acevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:Alteration in cell volume of vertebrates results in activation of volume-sensitive ion flux pathways. Fine control of the activity of these pathways enables cells to regulate volume following osmotic perturbation. Protein phosphorylation and dephosphorylation have been reported to play a crucial role in the control of volume-sensitive ion flux pathways. Exposing Amphiuma tridactylu red blood cells (RBCs) to phorbol esters in isotonic medium results in a simultaneous, dose-dependent activation of both Na+/H+ and K+/H+ exchangers. We tested the hypothesis that in Amphiuma RBCs, both shrinkage-induced Na+/H+ exchange and swelling-induced K+/H+ exchange are activated by phosphorylation-dependent reactions. To this end, we assessed the effect of calyculin A, a phosphatase inhibitor, on the activity of the aforementioned exchangers. We found that exposure of Amphiuma RBCs to calyculin-A in isotonic media results in simultaneous, 1–2 orders of magnitude increase in the activity of both K+/H+ and Na+/H+ exchangers. We also demonstrate that, in isotonic media, calyculin A-dependent increases in net Na+ uptake and K+ loss are a direct result of phosphatase inhibition and are not dependent on changes in cell volume. Whereas calyculin A exposure in the absence of volume changes results in stimulation of both the Na+/H+ and K+/H+ exchangers, superimposing cell swelling or shrinkage and calyculin A treatment results in selective activation of K+/H+ or Na+/H+ exchange, respectively. We conclude that kinase-dependent reactions are responsible for Na+/H+ and K+/H+ exchange activity, whereas undefined volume-dependent reactions confer specificity and coordinated control.
Robert R Rigor - One of the best experts on this subject based on the ideXlab platform.
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coordinated control of volume regulatory na h and k h exchange pathways in Amphiuma red blood cells
American Journal of Physiology-cell Physiology, 2010Co-Authors: Alejandro Ortizacevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:The Na+/H+ and K+/H+ exchange pathways of Amphiuma tridactylum red blood cells (RBCs) are quiescent at normal resting cell volume yet are selectively activated in response to cell shrinkage and swe...
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Coordinated control of volume regulatory Na+/H+ and K+/H+ exchange pathways in Amphiuma red blood cells.
American journal of physiology. Cell physiology, 2009Co-Authors: Alejandro Ortiz-acevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:The Na+/H+ and K+/H+ exchange pathways of Amphiuma tridactylum red blood cells (RBCs) are quiescent at normal resting cell volume yet are selectively activated in response to cell shrinkage and swe...
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activation of na h and k h exchange by calyculin a in Amphiuma tridactylum red blood cells implications for the control of volume induced ion flux activity
American Journal of Physiology-cell Physiology, 2008Co-Authors: Alejandro Ortizacevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:Alteration in cell volume of vertebrates results in activation of volume-sensitive ion flux pathways. Fine control of the activity of these pathways enables cells to regulate volume following osmotic perturbation. Protein phosphorylation and dephosphorylation have been reported to play a crucial role in the control of volume-sensitive ion flux pathways. Exposing Amphiuma tridactylu red blood cells (RBCs) to phorbol esters in isotonic medium results in a simultaneous, dose-dependent activation of both Na+/H+ and K+/H+ exchangers. We tested the hypothesis that in Amphiuma RBCs, both shrinkage-induced Na+/H+ exchange and swelling-induced K+/H+ exchange are activated by phosphorylation-dependent reactions. To this end, we assessed the effect of calyculin A, a phosphatase inhibitor, on the activity of the aforementioned exchangers. We found that exposure of Amphiuma RBCs to calyculin-A in isotonic media results in simultaneous, 1–2 orders of magnitude increase in the activity of both K+/H+ and Na+/H+ exchangers. We also demonstrate that, in isotonic media, calyculin A-dependent increases in net Na+ uptake and K+ loss are a direct result of phosphatase inhibition and are not dependent on changes in cell volume. Whereas calyculin A exposure in the absence of volume changes results in stimulation of both the Na+/H+ and K+/H+ exchangers, superimposing cell swelling or shrinkage and calyculin A treatment results in selective activation of K+/H+ or Na+/H+ exchange, respectively. We conclude that kinase-dependent reactions are responsible for Na+/H+ and K+/H+ exchange activity, whereas undefined volume-dependent reactions confer specificity and coordinated control.
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Activation of Na+/H+ and K+/H+exchange by calyculin A in Amphiuma tridactylum red blood cells : implications for the control of volume-induced ion flux activity
American journal of physiology. Cell physiology, 2008Co-Authors: Alejandro Ortiz-acevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:Alteration in cell volume of vertebrates results in activation of volume-sensitive ion flux pathways. Fine control of the activity of these pathways enables cells to regulate volume following osmotic perturbation. Protein phosphorylation and dephosphorylation have been reported to play a crucial role in the control of volume-sensitive ion flux pathways. Exposing Amphiuma tridactylu red blood cells (RBCs) to phorbol esters in isotonic medium results in a simultaneous, dose-dependent activation of both Na+/H+ and K+/H+ exchangers. We tested the hypothesis that in Amphiuma RBCs, both shrinkage-induced Na+/H+ exchange and swelling-induced K+/H+ exchange are activated by phosphorylation-dependent reactions. To this end, we assessed the effect of calyculin A, a phosphatase inhibitor, on the activity of the aforementioned exchangers. We found that exposure of Amphiuma RBCs to calyculin-A in isotonic media results in simultaneous, 1–2 orders of magnitude increase in the activity of both K+/H+ and Na+/H+ exchangers. We also demonstrate that, in isotonic media, calyculin A-dependent increases in net Na+ uptake and K+ loss are a direct result of phosphatase inhibition and are not dependent on changes in cell volume. Whereas calyculin A exposure in the absence of volume changes results in stimulation of both the Na+/H+ and K+/H+ exchangers, superimposing cell swelling or shrinkage and calyculin A treatment results in selective activation of K+/H+ or Na+/H+ exchange, respectively. We conclude that kinase-dependent reactions are responsible for Na+/H+ and K+/H+ exchange activity, whereas undefined volume-dependent reactions confer specificity and coordinated control.
Albert L. Bryan - One of the best experts on this subject based on the ideXlab platform.
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Radiocesium (137Cs) concentrations in the two-toed Amphiuma (Amphiuma means) and the lesser siren (Siren intermedia).
Journal of environmental radioactivity, 2019Co-Authors: David L. Haskins, Albert L. BryanAbstract:Abstract This study sought to determine radiocesium (137Cs) concentrations in two species of aquatic salamanders – the two-toed Amphiuma (Amphiuma means) and the lesser siren (Siren intermedia) on the Savannah River Site. Concentrations (137Cs Bq/g, dry wt) of the two species were similar at both 137Cs-contaminated (A. means = 0.733 ± 0.242, n = 5; S. intermedia = 0.839 ± 0.722, n = 5) and reference sites (A. means = 0.028 ± 0.020, n = 5; S. intermedia = 0.042 ± 0.027, n = 11). Salamanders captured in areas impacted by 137Cs contamination exhibited significantly higher 137Cs concentrations than individuals captured at reference sites (U = 146, p
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Mercury Concentrations in the Two-Toed Amphiuma (Amphiuma means) and the Lesser Siren (Siren intermedia): Validating Non-lethal Sampling Methods in Southeastern Aquatic Salamanders
Archives of Environmental Contamination and Toxicology, 2019Co-Authors: David L. Haskins, Alexis M. Korotasz, Albert L. BryanAbstract:The global decline of amphibians is a major conservation issue. Many stressors are recognized for this decline including exposure to environmental contaminants. Mercury (Hg) is an environmental contaminant that bioaccumulates in wildlife and can cause a variety of negative impacts across taxa, including amphibians. Amphiuma and Siren spp. can comprise a large portion of biomass within their respective ecosystems, and thus, likely serve as important predators or prey in wetland communities. However, due to their cryptic nature, little is known about their ecology, diet, and accumulation potential. We sought to validate a nonlethal sampling method to quantify total mercury (THg) in two enigmatic species of aquatic salamanders: the two-toed Amphiuma ( Amphiuma means ) and the lesser siren ( Siren intermedia ). We examined relationships between THg content in lethal (whole-body) and nonlethal (tail clip) samples. Tail clips were statistically significant predictors of whole-body THg (all p
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mercury concentrations in the two toed Amphiuma Amphiuma means and the lesser siren siren intermedia validating non lethal sampling methods in southeastern aquatic salamanders
Archives of Environmental Contamination and Toxicology, 2019Co-Authors: David L. Haskins, Alexis M. Korotasz, Albert L. BryanAbstract:The global decline of amphibians is a major conservation issue. Many stressors are recognized for this decline including exposure to environmental contaminants. Mercury (Hg) is an environmental contaminant that bioaccumulates in wildlife and can cause a variety of negative impacts across taxa, including amphibians. Amphiuma and Siren spp. can comprise a large portion of biomass within their respective ecosystems, and thus, likely serve as important predators or prey in wetland communities. However, due to their cryptic nature, little is known about their ecology, diet, and accumulation potential. We sought to validate a nonlethal sampling method to quantify total mercury (THg) in two enigmatic species of aquatic salamanders: the two-toed Amphiuma (Amphiuma means) and the lesser siren (Siren intermedia). We examined relationships between THg content in lethal (whole-body) and nonlethal (tail clip) samples. Tail clips were statistically significant predictors of whole-body THg (all p < 0.001), explaining 84–89% of variation in whole-body THg. Average whole-body THg (mg/kg) did not significantly differ between the two species (p = 0.97), and overall, they had similar whole-body THg content (S. intermedia = 0.330 ± 0.04, n = 18; A. means = 0.333 ± 0.07, n = 11). To our knowledge, these data represent the first reported Hg burdens in A. means and S. intermedia.
Alejandro Ortiz-acevedo - One of the best experts on this subject based on the ideXlab platform.
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Coordinated control of volume regulatory Na+/H+ and K+/H+ exchange pathways in Amphiuma red blood cells.
American journal of physiology. Cell physiology, 2009Co-Authors: Alejandro Ortiz-acevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:The Na+/H+ and K+/H+ exchange pathways of Amphiuma tridactylum red blood cells (RBCs) are quiescent at normal resting cell volume yet are selectively activated in response to cell shrinkage and swe...
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Activation of Na+/H+ and K+/H+exchange by calyculin A in Amphiuma tridactylum red blood cells : implications for the control of volume-induced ion flux activity
American journal of physiology. Cell physiology, 2008Co-Authors: Alejandro Ortiz-acevedo, Robert R Rigor, Hector M Maldonado, Peter M CalaAbstract:Alteration in cell volume of vertebrates results in activation of volume-sensitive ion flux pathways. Fine control of the activity of these pathways enables cells to regulate volume following osmotic perturbation. Protein phosphorylation and dephosphorylation have been reported to play a crucial role in the control of volume-sensitive ion flux pathways. Exposing Amphiuma tridactylu red blood cells (RBCs) to phorbol esters in isotonic medium results in a simultaneous, dose-dependent activation of both Na+/H+ and K+/H+ exchangers. We tested the hypothesis that in Amphiuma RBCs, both shrinkage-induced Na+/H+ exchange and swelling-induced K+/H+ exchange are activated by phosphorylation-dependent reactions. To this end, we assessed the effect of calyculin A, a phosphatase inhibitor, on the activity of the aforementioned exchangers. We found that exposure of Amphiuma RBCs to calyculin-A in isotonic media results in simultaneous, 1–2 orders of magnitude increase in the activity of both K+/H+ and Na+/H+ exchangers. We also demonstrate that, in isotonic media, calyculin A-dependent increases in net Na+ uptake and K+ loss are a direct result of phosphatase inhibition and are not dependent on changes in cell volume. Whereas calyculin A exposure in the absence of volume changes results in stimulation of both the Na+/H+ and K+/H+ exchangers, superimposing cell swelling or shrinkage and calyculin A treatment results in selective activation of K+/H+ or Na+/H+ exchange, respectively. We conclude that kinase-dependent reactions are responsible for Na+/H+ and K+/H+ exchange activity, whereas undefined volume-dependent reactions confer specificity and coordinated control.