[The effect of the acidification of the extracellular medium on the membrane sodium currents of single heart cells].
The effect of a drop of extracellular pH on the fast and slow sodium currents (INaf and INas) was studied in the rat isolated perfused ventricular myocytes. The shift of the extracellular pH value from 7.4 to 5.0 caused a disappearance of INaf. If the fast sodium current was blocked by external tetrodotoxin (10(-6) mol/l) or inactivated by the shift of the maintaining potential from -120 to -70 mV. the external pH drop from 7.4 to 5.0 only caused a slight diminishing of the slow sodium current amplitude. INas kinetics and potential-dependent properties were unaffected. INas was blocked at the external pH values lower than 4.0. The data obtained suggests that INaf and INas of isolated single cardiomyocytes have a different sensitivity to external pH: INaf is more sensitive to the acidification of the external medium than INas.
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D000818:Animals; D006321:Heart / Q000502:physiology*; D006352:Heart Ventricles / Q000166:cytology; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology; D009206:Myocardium / Q000166:cytology*; D010477:Perfusion / Q000379:methods; D051381:Rats; D015222:Sodium Channels / Q000502:physiology*; D016276:Ventricular Function
D015222:Sodium Channels
Vliianie zakisleniia vnekletochnoĭ sredy na natrievye toki membrany odinochnykh kletok serdtsa.