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Electrophysiology and noise analysis of potassium ion depolarized epithelia of frog rana pipiens skin


American Journal of Physiology 249(5 PART 1): C421-C429
Electrophysiology and noise analysis of potassium ion depolarized epithelia of frog rana pipiens skin
Epithelia of frog skin bathed either symmetrically with a sulfate-Ringer solution or bathed asymmetrically and depolarized with a 112 mM K+ basolateral solution (Kb+) were studied with intracellular microelectrode techniques. Kb+ depoliarization caused an initial decrease of the short-circuit current (Isc) with a subsequent return of the Isc toward control values in 60-90 min. Whereas basolateral membrane resistance (Rb) and voltage were decreased markedly by high [Kb+], apical membrane electrical resistance (Ra) was decreased also. After 60 min intracellular voltage averaged -27.3 mV, transcellular fractional resistance (fRa) was 86.8%, and Ra and Rb were decreased to 36.1 and 13.0%, of their control values, respectively. Amiloride-induced noise analysis of the apical membrane Na+ channels revealed that Na+ channel density was increased .apprx. 72% while single-channel Na+ current was decreased to 39.9% of control, roughly proportional to the decrease of apical membrane voltage (34.0% of control). In control and Kb+-depolarized epithelia, the Na+ channel density exhibited a phenomenon of autoregulation. Inhibition of Na+ entry (by amiloride) caused large increases of Na+ channel density toward saturating values of .apprx. 520 .times. 106 channels/cm2 in Kb+-depolarized tissues.


Accession: 005349880



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