Intracellular calcium regulates basolateral potassium channels in a chloride-secreting epithelium.
The two individual cell membranes of epithelia are functionally coupled, so that changes in apical membrane conductance are paralleled by changes in basolateral K+ conductance. However, the signal that regulates basolateral K+ conductance, thereby coupling the two membranes, is unknown. We tested the hypothesis that the cellular calcium concentration, [Ca2+]c, may regulate basolateral K+ conductance in canine tracheal epithelium, a Cl- -secreting epithelium that shows marked membrane coupling. Three findings support the hypothesis. First, the intracellular Ca2+ antagonist 8-(diethylamino)octyl 3,4,5-trimethoxybenzoate hydrochloride (TMB-8) attenuated the secretory response. Second, the secretagogue epinephrine increased [Ca2+]c, as measured with quin-2. Third, we found a K+ channel that was activated by Ca2+ on the cytosolic side of the membrane. Thus, cytosolic Ca2+ regulates the basolateral K+ conductance and may be the signal responsible for functional coupling of the two cell membranes.
Welsh
M J
MJ
McCann
J D
JD
D000818:Animals; D002118:Calcium / Q000502:physiology*; D002712:Chlorides / Q000378:metabolism*; D004285:Dogs; D004553:Electric Conductivity; D004837:Epinephrine / Q000494:pharmacology; D004848:Epithelium / Q000502:physiology; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D011188:Potassium / Q000502:physiology*; D012636:Secretory Rate / Q000187:drug effects; D014132:Trachea / Q000502:physiology*
D002712:Chlorides; D007473:Ion Channels; C006014:8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate; D005707:Gallic Acid; D011188:Potassium; D002118:Calcium; D004837:Epinephrine