A novel cGMP-activated Cl- channel in renal proximal tubules.
Cl- channels activated by natriuretic peptides were detected in cultured rat proximal convoluted tubule (PCT) cells with the use of patch-clamp methodology. Bath application of atrial natriuretic peptide (ANP) activates a 150-pS Cl- channel with the open probability (Po) of the channel increasing from 0.0008 +/- 0.0003 to 0.021 +/- 0.008. 8-Bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP), a membrane-permeable analogue of cGMP, increased channel activity in the on-cell mode. In inside-out patches the channel was activated by cGMP in a dose-dependent manner. Channel activity decreased after washing out and increased on reapplication of cGMP. A similar activation was observed also in presence of either of two protein kinase inhibitors, N-[2-(methylamino)ethyl]-5-isoquinolinesulfonamide dihydrochloride or KT5823, or a phosphatase inhibitor. Bath application of urodilatin mimicked the action of ANP. Po of the channel was found to be independent of both voltage and Ca2+, and gating activity could be blocked by the stilbene, 4,4-dinitrostilbene-2,2-disulfonic acid. These results demonstrate a Cl- conductance in PCT cells modulated by ANP and urodilatin via their second messenger, cGMP.
Darvish
N
N
Department of Physiology and Biophysics, Bruce Rappaport Faculty of Medicine, Haifa, Israel.
Winaver
J
J
Dagan
D
D
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D018118:Chloride Channels / Q000187:drug effects* / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D010446:Peptide Fragments / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D018118:Chloride Channels; D010446:Peptide Fragments; C016276:8-bromocyclic GMP; C056452:Ularitide; D009320:Atrial Natriuretic Factor; D006152:Cyclic GMP; D002118:Calcium