Membrane responses to changes in the extracellular potassium concentration in isolated hippocampal pyramidal neurons

Autor: Pinchenko Vo, T. M. Volkova, Oleg Krishtal, V. M. Filippov
Rok vydání: 1998
Předmět:
Zdroj: Scopus-Elsevier
ISSN: 1573-9007
0090-2977
DOI: 10.1007/bf02462833
Popis: The responses of freshly isolated hippocampal pyramidal neurons to rapid, elevations of the external potassium concentration ([K+] out ) were investigated using the whole-cell variation of a patch-clamp technique. An elevation of [K+] out induced a two-phase inward current at the membrane potentials more negative than the reversal potential for K ions. This current consisted of a leakage, current and a time-dependent current (τ=40–50 msec at 21°C), the latter designated below asI ΔK. It displayed first-order activation kinetics that showed neither voltage, nor concentration dependence. The amplitude of this current was determined by the external K+ concentration and increased with hyperpolarization. Voltage dependence ofI ΔK measured within the range from −20 to −120 mV was similar to that for inward rectifier. Activation ofI ΔK was utterly dependent on Na+; substitution of extracellular Na+ with choline chloride almost completely depressedI ΔK.I ΔK was absent in the cells freshly dissociated from the nodosal and dorsal root ganglia. This suggests that this earlier unrecognized current is instrumental in preserving densely packed hippocampal pyramidal neurons from sudden increases in [K+] out and following spontaneous over-excitation. It prevents the neurons from responding to K+-induced depolarizations by slowing down potassium influx.
Databáze: OpenAIRE
Externí odkaz: