View of K+ secretion through the apical K channel of cortical collecting duct.
The apical small-conductance K+ channel plays an important role in renal K+ secretion, as evidenced by the presence of the extensive modulatory pathways. Figure 3 summarizes the current understanding of the mechanisms that modulate the apical small-conductance K+ channel. Stimulation of adenylate cyclase enhances channel activity and consequently K+ secretion. In contrast, increases in intracellular Ca2+ concentration and activation of Ca(2+)-dependent signal transduction pathways inhibit the K+ channel and thus decrease K+ secretion. The vasopressin-induced stimulation of K+ secretion in CCD results at least in part from cAMP-dependent signal transduction pathways. The Ca(2+)-dependent signal transduction pathway is responsible for modulatory coupling between Na+ pump turnover and apical K+ conductance when the Na+ pump is inhibited.
Wang
W H
WH
Department of Pharmacology, New York Medical College, Valhalla, USA.
D000199:Actins / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D004563:Electrochemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007685:Kidney Tubules, Collecting / Q000187:drug effects / Q000378:metabolism*; D008954:Models, Biological; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D017419:Potassium, Dietary / Q000008:administration & dosage; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism; D014667:Vasopressins / Q000494:pharmacology
D000199:Actins; D015221:Potassium Channels; D017419:Potassium, Dietary; D014667:Vasopressins; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D002118:Calcium