THE ELECTROGENESIS OF ADRENALINE-HYPER-POLARIZATION OF SYMPATHETIC GANGLION CELLS IN BULLFROGS

Abstract

Bullfrog sympathetic ganglion cells produced hyperpolarizing (Ad-hyperpolarization) and depolarizing (Ad-depolarization) responses when adrenaline (Ad) was directly applied to ganglia. The nature of Ad-hyperpolarization recorded by the sucrose-gap method was analysed in the present experiment, in order to clarify its electrogenesis. The amplitude of Ad-hyperpolarization was increased or decreased while ganglion cell membranes were hyperpolarized or depolarized, respectively, by applying a moderate conditioning current to the ganglia. The Adhyperpolarization was depressed in K⁺-rich solutions as well as in K⁺-deficient solutions. It was not significantly altered by replacing the extracellular total Cl ions by equimolar glutamate or thiosulfate ions. Ad-hyperpolarization was depressed and finally abolished in the Na⁺-free Tris solution, and was reversibly eliminated in the solution where Na ions weretotally replaced by equimolar Li ions. It was enhanced when a preparation was previously perfused in the K⁺-free, Na⁺-rich solution for certain periods, during which the intracellular Na⁺ concentration might be increased. Ad-hyperpolarization was depressed by lowering the temperature and by the action of ouabain, and the amplitude of Ad-hyperpolarization was markedly increased in the presence of TEA. The ionic mechanism underlying the generation of Ad-hyperpolarization was discussed on the basis of these present experimental results, and it was suggested that Ad-hyperpolarization might be generated by an electrogenic sodium pump.