Vasopressin increases density of apical low-conductance K+ channels in rat CCD.
The effect of arginine vasopressin (AVP) on the low-conductance K+ channel in the apical membrane of rat cortical collecting duct (CCD) principal cells from animals on a control and high-K+ diet was studied using patch-clamp techniques. AVP stimulated apical low-conductance K+ channel activity in both control and high-K+ animals: application of 110-220 pM AVP induced a significant increase in the density of low-conductance K+ channels. In the presence of phosphodiesterase inhibitor (3-isobutyl-1-methylxanthine), administration of 22 pM AVP also increased channel activity. The action of AVP on low-conductance K+ channel activity was mimicked by simultaneous application of forskolin and 3-isobutyl-1-methylxanthine. Exogenously applied N6,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (dibutyryl-cAMP, 0.4-0.8 mM) also increased apical low-conductance K+ channel activity. Since channel open probability (Po) was almost saturated in the absence of AVP, the increase of channel activity induced by AVP, forskolin, and dibutyryl-cAMP resulted predominantly from stimulating previously silent K+ channels. We conclude that AVP induces an increase of low-conductance K+ channel activity of principal cells in rat CCD by the stimulation of cAMP-dependent protein kinase. The AVP-induced increase of low-conductance K+ channel activity can thus significantly contribute to the hormone-induced K+ secretion in the rat CCD.
Cassola
A C
AC
Department of Cellular and Molecular Physiology, School of Medicine, Yale University, New Haven, Connecticut 06510.
Giebisch
G
G
Wang
W
W
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology*; D003994:Bucladesine / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004553:Electric Conductivity; D005260:Female; D007672:Kidney Cortex / Q000378:metabolism*; D007685:Kidney Tubules, Collecting / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010766:Phosphorylation; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
D015221:Potassium Channels; D001127:Arginine Vasopressin; D005576:Colforsin; D003994:Bucladesine; D000242:Cyclic AMP; D015056:1-Methyl-3-isobutylxanthine