title: Luminal arginine vasopressin stimulates Na(+)-H+ exchange and H(+)-ATPase in cortical distal tubule via V1 receptor.
abstract: Bicarbonate reabsorption was evaluated by stationary microperfusion of in vivo early distal (ED) and late distal (LD) segments of rat kidney. Intratubular pH was recorded by double-barreled H ion-exchange resin/reference (1 M KCl) microelectrodes for the determination of HCO3- reabsorption. In the presence of luminal arginine vasopressin (AVP, 10(-9) M), a significant increase in HCO3- reabsorption was observed both in ED (from 0.931 +/- 0.061 to 2.12 +/- 0.171 nmol.cm-2.s-1] and LD segments [from 0.542 +/- 0.086 to 1.67 +/- 0.111 nmol.cm-2.s-1]. The addition of the V1-receptor antagonist [(d (CH2)5, Tyr (Et)2) arginine vasopressin] (10(-5) M) to luminal perfusion blocked luminal AVP mediated stimulation in ED and LD segments. 5-(N, N-hexamethylene) amiloride (10(-4) M) added to luminal perfusion inhibited luminal AVP-mediated stimulation in ED (by 63.7%) and LD (by 34.1%) segments. The addition of Bafilomycin A1 (2 x 10(-7) M) to the luminal perfusion did not affect luminal AVP-mediated stimulation in ED segments, but reduced it (by 31.7%) in LD segments. Our results indicate that luminal AVP acts to stimulate the Na(+)-H+ exchange in ED and LD segments via activation of V1 receptors, as well as the vacuolar H(+)-ATPase in LD segments.
authors.affiliation: Department of Physiology and Biophysics, University of São Paulo, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Barreto-Chaves
authors.forename: M
authors.initials: M
authors.lastname: de Mello-Aires
mesh_terms: D000584:Amiloride / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D065092:Antidiuretic Hormone Receptor Antagonists; D001127:Arginine Vasopressin / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007672:Kidney Cortex; D007686:Kidney Tubules, Distal / Q000201:enzymology*; D018942:Macrolides; D008297:Male; D009994:Osmolar Concentration; D006180:Proton-Translocating ATPases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D017483:Receptors, Vasopressin / Q000502:physiology*; D017923:Sodium-Hydrogen Exchangers / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D065092:Antidiuretic Hormone Receptor Antagonists; D004791:Enzyme Inhibitors; D018942:Macrolides; D017483:Receptors, Vasopressin; D017923:Sodium-Hydrogen Exchangers; D001127:Arginine Vasopressin; C057360:5-(N,N-hexamethylene)amiloride; D000584:Amiloride; C040929:bafilomycin A1; D006180:Proton-Translocating ATPases