Arginine vasopressin stimulates H+-ATPase in MDCK cells via V1(cell Ca2+) and V2(cAMP) receptors

Abstract

The effect of arginine vasopressin (AVP) and/or atrial natriuretic peptide (ANP) on the regulation of intracellular pH (pHi) via H+-ATPase and of cytosolic calcium ([Ca2+]i) was investigated in Madin-Darby canine kidney (MDCK) cells by the fluorescent probes BCECF-AM and fluo-4-AM, respectively. The pHirecovery rate was examined after intracellular acidification following an NH4Cl pulse, in the presence of zero Na+plus Schering 28080 (a specific inhibitor of H+-K+-ATPase). AVP (10-12-10-6M) increased the rate of pHirecovery and [Ca2+]iin a dose-dependent manner. V1- or V2-receptor antagonists impaired the effect of AVP on both processes, and DDAVP (10-12-10-6M; a V2-selective agonist) caused a dose-dependent stimulation of them. [Ca2+]ior cAMP (as increased by 10-5M thapsigargin or 8-BrcAMP, respectively) alone had no effect on H+-ATPase, but their synergic action was necessary to stimulate H+-ATPase. In agreement with these findings, ANP (10-6M) or dimethyl-BAPTA-AM (5 × 10-5M), impairing the increase of [Ca2+]iin response to AVP, blocks the stimulatory effect of AVP on H+-ATPase.