Electrophysiological study on the high K+ sensitivity of rat glomerulosa cells.
Elevation of extracellular potassium concentration by as little as some tenth of mM activates rat adrenal glomerulosa cells. In the present study some factors responsible for this high K+ sensitivity were examined. Using whole-cell voltage-clamp technique we found that both T-type and L-type voltage-dependent Ca2+ channels have very low threshold potential (-71 and -58 mV, resp.). By means of patch-clamp technique combined with single-cell fluorimetry we also provided evidence that the activation of Igl, a K+-activated inward rectifying current is associated with Ca2+ influx. Both the low activation threshold of voltage-dependent Ca2+ channels and the function of Igl contribute to the exceptional K+ sensitivity of the glomerulosa cells.
Várnai
P
P
Department of Physiology and Laboratory of Cellular and Molecular Physiology, Semmelweis University of Medicine, H-1444 Budapest, P.O. Box 259, Hungary.
Petheö
G L
GL
Makara
J K
JK
Spät
A
A
D000818:Animals; D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004553:Electric Conductivity; D004594:Electrophysiology; D005470:Fluorometry; D008564:Membrane Potentials; D018408:Patch-Clamp Techniques; D011188:Potassium / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D015384:Zona Glomerulosa / Q000187:drug effects* / Q000502:physiology*
D015220:Calcium Channels; D011188:Potassium; D002118:Calcium