Changes of intracellular potassium activity and membrane potential in guinea pig ventricular myocardium during superfusion with low sodium solutions and effects of low pH |
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Authors: | LIU Bei-ying NIU Wei-zhen |
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Institution: | Department of Cardiovascular Physiology, Capital University of Medical Sciences, Beijing 100054, China |
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Abstract: | AIM:To investigate the changes in intracellular potassium activity(aiK) and membrane potential(Vm) induced by low external sodium infusion (Low Na]o) and to detect the mechanisms involved and the relationship between aiK and Vm. METHODS:aiK and Vm were measured in infusion with different sodium concentrations using methods of convenient and ion selective microelectrodes in guinea pig ventricular myocardium. RESULTS:Low Na]o resulted in a decrease in aiK and an increase in Vm in a Na+ concentration-dependent manner.At the same time,contraction and resting potential increased, and action potential duration decreased markedly,but action potential amplitude was not affected. A change of the pH from 7.4 to 7.0 in low Na]o solution reduced the decrease in aiK, but did not affect the increase in Vm.CONCLUSION:A better linear relationship appeared between the changes in aik and Na]o or in Vm and Na]o,while during each low Na]o the change in both aiK or Vm may reach a new balance level. |
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Keywords: | Potassium Sodium Membrane potentials Action potentials Myocardium Guinea pigs |
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