Na+-dependent CI-HCOs Exchange in the Squid Axon Dependence on ExtraceUular pH
نویسندگان
چکیده
Address reprint requests to Dr. Walter F. Boron, Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06510-2989. j. GEN. PHYSIOL. © The Rockefeller University Press • 0022-1295/92/05/0817/21 $2.00 Volume 99 May 1992 817-837 817 on A ril 8, 2017 D ow nladed fom Published May 1, 1992
منابع مشابه
Voltage dependence of the Na/Ca exchange in voltage-clamped, dialyzed squid axons. Na-dependent Ca efflux
A combination of the voltage-clamp and the intracellular dialysis techniques has been used to study the membrane potential dependence of the Nao-dependent Ca efflux in squid giant axons. In order to improve axon survival, experiments were carried out using internal solutions prepared with large impermeant organic anions and cations, which did not affect the operation of the Na/Ca exchange mecha...
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The intracellular pH-regulating mechanism of the squid axon was examined for its dependence on the concentrations of external Na+ and HCO3-, always at an external pH (pHo) of 8.0. Axons having an initial intracellular pH (pHi) of approximately 7.4 were internally dialyzed with a solution of pH 6.5 that contained 400 mM Cl- and no Na+. After pHi had fallen to approximately 6.6, dialysis was halt...
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We propose a steady-state kinetic model for the squid Na(+)/Ca(2+) exchanger that differs from other current models of regulation in that it takes into account, within a single kinetic scheme, all ionic [intracellular Ca(2+) (Ca(i)(2+))-intracellular Na(+) (Na(i)(+))-intracellular H(i)(+)] and metabolic (ATP) regulations of the exchanger in which the Ca(i)(2+)-regulatory pathway plays the centr...
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The Na(+)/Ca(2+) exchanger's family of membrane transporters is widely distributed in cells and tissues of the animal kingdom and constitutes one of the most important mechanisms for extruding Ca(2+) from the cell. Two basic properties characterize them. 1) Their activity is not predicted by thermodynamic parameters of classical electrogenic countertransporters (dependence on ionic gradients an...
متن کاملNa(+)-dependent Cl-HCO3 exchange in the squid axon. Dependence on extracellular pH
Intracellular pH (pHi) in squid giant axons recovers from acid loads by means of a Na(+)-dependent Cl-HCO3 exchanger, the actual mechanism of which might be exchange of: (i) external Na+ and HCO3- for internal Cl- and H+, (ii) Na+ plus two HCO3- for Cl-, (iii) Na+ and CO3= for Cl-, or (iv) the NaCO3- ion pair for Cl-. Here we examine sensitivity of transport to changes of extracellular pH (pHo)...
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