Involvement of calmodulin and protein kinase C in the regulation of K+ transport by carbachol across the rat distal colon.
The cholinergic agonist carbachol stimulates the apical H+-K+-ATPase and apical as well as basolateral K+ channels in the rat distal colon. The effect of carbachol was tested in the presence of different inhibitors of the Ca2+ signaling pathway in order to characterize the intracellular mechanisms involved. Both carbachol-stimulated Rb+-efflux as well as carbachol-stimulated mucosal Rb+-uptake were dependent on the presence of serosal Ca2+. The Ca2+-calmodulin antagonist calmidazolium (10(-7) mol l(-1)) inhibited the stimulation of mucosal and serosal Rb+ efflux by carbachol. A similar effect had KN-62 (10(-5) mol l(-1)), an inhibitor of the Ca2+-calmodulin-dependent kinase II, suggesting the regulation of basolateral and apical K+ channels by this kinase. Staurosporine (10(-6) mol l(-1)), which potently inhibits protein kinase C, did not alter the effect of carbachol on Rb+ efflux, although the stimulation of apical Rb+ efflux by carbachol seemed to be less prolonged, indicating that protein kinase C is not involved in the regulation of K+ permeability. In contrast, mucosal Rb+ uptake, which is determined by the ouabain- and vanadate-sensitive K+ transport via the apical H+-K+-ATPase, was decreased to nearly one third of control values in the presence of calmidazolium. Both calmidazolium and staurosporine, but not KN-62, prevented the stimulatory action of carbachol on the H+-K+-ATPase, suggesting a synergistic control of this ion pump by both Ca2+-calmodulin and protein kinase C.
Heinke
B
B
Institut für Veterinär-Physiologie, Justus-Liebig-Universität Giessen, Germany.
Ribeiro
R
R
Diener
M
M
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D002147:Calmodulin / Q000502:physiology*; D002217:Carbachol / Q000494:pharmacology*; D018679:Cholinergic Agonists / Q000494:pharmacology*; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D011188:Potassium / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012414:Rubidium Radioisotopes / Q000493:pharmacokinetics; D019311:Staurosporine / Q000494:pharmacology
D002147:Calmodulin; D018679:Cholinergic Agonists; D016861:Cyclooxygenase Inhibitors; D004791:Enzyme Inhibitors; D007093:Imidazoles; D012414:Rubidium Radioisotopes; C031938:calmidazolium; C063302:KN 62; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D002217:Carbachol; D011493:Protein Kinase C; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D019311:Staurosporine; D011188:Potassium; D002118:Calcium; D007213:Indomethacin