Activation of the Na Pump Current by External K and Cs Ions in Cardioballs from Sheep Purkinje Fibres

Overview

Journal Pflugers Arch

Specialty Physiology

Date 1989 May 1

PMID 2726440

Citations 5

Authors

H G GLITSCH

T Krahn

F Verdonck

Affiliations

Soon will be listed here.

Abstract

The Na pump current (Ip) was measured at 30-33 degrees C as a function of the extracellular K+ or Cs+ concentrations ([K]o; [Cs]o) by means of whole cell recording from cardioballs isolated from sheep Purkinje fibres. The results show that the magnitude of Ip is an s-shaped, saturating function of [K]o or [Cs]o, respectively. Half maximal Ip activation occurs at 1.2 mM Ko or 3.2 mM Cso (clamp potential: -20 mV). These values are appreciably lower than earlier measurements on sheep Purkinje fibres indicated. The Hill coefficients for Ip activation by external K+ or Cs+ were calculated to be 1.94 and 1.73, respectively. The numbers suggest that Ip activation requires at least two external activator cations.

Citing Articles

Voltage-dependent inhibition of the sodium pump by external sodium: species differences and possible role of the N-terminus of the alpha-subunit.

Vasilets L, Ohta T, Noguchi S, Kawamura M, Schwarz W Eur Biophys J. 1993; 21(6):433-43.

PMID: 8383596 DOI: 10.1007/BF00185871.

The Na+/K+ pump of cardiac Purkinje cells is preferentially fuelled by glycolytic ATP production.

GLITSCH H, Tappe A Pflugers Arch. 1993; 422(4):380-5.

PMID: 8382364 DOI: 10.1007/BF00374294.

Effects of cesium on cellular systems.

Ghosh A, Sharma A, Talukder G Biol Trace Elem Res. 1993; 38(2):165-203.

PMID: 7508252 DOI: 10.1007/BF02784052.

The mechanism of rectification of iK1 in canine Purkinje myocytes.

Oliva C, Cohen I, Pennefather P J Gen Physiol. 1990; 96(2):299-318.

PMID: 1698915 PMC: 2228993. DOI: 10.1085/jgp.96.2.299.

Dependence of Na+ pump current on external monovalent cations and membrane potential in rabbit cardiac Purkinje cells.

Bielen F, GLITSCH H, Verdonck F J Physiol. 1991; 442:169-89.

PMID: 1665855 PMC: 1179884. DOI: 10.1113/jphysiol.1991.sp018788.

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