Sensitization of Ca(2+)-dependent K(+)-channels in Guinea-pig pancreatic acinar cells by phosphorylation.
The effects of adenosine 3', 5'-cyclic monophosphate (cAMP)-dependent protein phosphorylation on Ca(2+)-sensitivity of Ca(2+)-dependent K(+)-channels in guinea-pig pancreatic acinar cells were studied by patch-clamp single-channel methods. When opening of the channels did not occur in excised inside-out membrane patches exposed to 10(-6) M Ca2+, the addition of 25 U/ml catalytic units of cAMP-dependent protein kinase (PKA) to the bath solution opened the channels, with a conductance of 30 pS (in symmetrical K(+)-rich solution). The addition of a PKA-inhibitor (100 microM) extinguished the PKA-dependent opening of the K(+)-channels. Alkaline phosphatase (5 U/ml) reversed the PKA-dependent opening of the K(+)-channels to control levels (before PKA). These results demonstrate that cAMP-dependent protein phosphorylation initiates the Ca(2+)-sensitivity of the Ca(2+)-dependent K(+)-channels in guinea-pig pancreatic acinar cells.
Suzuki
K
K
Department of Bio-Medical Engineering, School of High-Technology for Human Welfare, Tokai University, Numazu Shizuoka, Japan.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000494:pharmacology; D006168:Guinea Pigs; D010179:Pancreas / Q000166:cytology / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010766:Phosphorylation; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*
D015221:Potassium Channels; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium