Regulation of K+ channels in the basolateral membrane of Necturus oxyntic cells.
Patch-clamp methods were used to study single-channel events in isolated oxyntic cells and gastric glands from Necturus maculosa. Cell-attached, excised inside-out and outside-out patches from the basolateral membrane frequently contained channels which had conductances of 67 +/- 21 pS in 24% of the patches and channels of smaller conductance, 33 +/- 6 pS in 56% of the patches. Channels in both classes were highly selective for K+ over Na+ and Cl-, and shared linear current-voltage relations. The 67-pS channel was activated by membrane depolarization, whereas the activity of the 33-pS channel was relatively voltage independent. The larger conductance channels were activated by intracellular Ca2+ in the range between 5 and 500 nM, but unaffected by cAMP. The smaller conductance channels were activated by cAMP, but not Ca2+. The presence of K+ channels in the basolateral membrane which are regulated by these known "second messengers" can account for the increase in conductance and the hyperpolarization of the membrane observed upon secretagogue stimulation.
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D004553:Electric Conductivity; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008954:Models, Biological; D009337:Necturus; D010295:Parietal Cells, Gastric / Q000502:physiology*; D011188:Potassium / Q000378:metabolism*
D007473:Ion Channels; D000001:Calcimycin; D003994:Bucladesine; D011188:Potassium; D002118:Calcium