title: Voltage and Ca2+-activated K+ channel in baso-lateral acinar cell membranes of mammalian salivary glands.
abstract: Nervous or hormonal stimulation of many exocrine glands evokes release of cellular K+ (ref. 1), as originally demonstrated in mammalian salivary glands2,3, and is associated with a marked increase in membrane conductance1,4,5. We now demonstrate directly, by using the patch-clamp technique6, the existence of a K+ channel with a large conductance localized in the baso-lateral plasma membranes of mouse and rat salivary gland acinar cells. The K+ channel has a conductance of approximately 250 pS in the presence of high K+ solutions on both sides of the membrane. Although mammalian exocrine glands are believed not to possess voltage-activated channels1,7, the probability of opening the salivary gland K+ channel was increased by membrane depolarization. The frequency of channel opening, particularly at higher membrane potentials, was increased markedly by elevating the internal ionized Ca2+ concentration, as previously shown for high-conductance K+ channels from cells of neural origin8-10. The Ca2+ and voltage-activated K+ channel explains the marked cellular K+ release that is characteristically observed when salivary glands are stimulated to secrete.
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004553:Electric Conductivity; D007473:Ion Channels / Q000187:drug effects / Q000502:physiology*; D008564:Membrane Potentials; D051379:Mice; D010306:Parotid Gland / Q000502:physiology; D011188:Potassium / Q000378:metabolism*; D051381:Rats; D012469:Salivary Glands / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D013363:Submandibular Gland / Q000502:physiology
chemical_list: D007473:Ion Channels; D011188:Potassium; D002118:Calcium