title: Genomic and nongenomic stimulatory effect of aldosterone on H+-ATPase in proximal S3 segments.
abstract: The genomic and nongenomic effects of aldosterone on the intracellular pH recovery rate (pHirr) via H(+)-ATPase and on cytosolic free calcium concentration ([Ca(2+)](i)) were investigated in isolated proximal S3 segments of rats during superfusion with an Na(+)-free solution, by using the fluorescent probes BCECF-AM and FLUO-4-AM, respectively. The pHirr, after cellular acidification with a NH(4)Cl pulse, was 0.064 ± 0.003 pH units/min (n = 17/74) and was abolished with concanamycin. Aldosterone (10(-12), 10(-10), 10(-8), or 10(-6) M with 1-h or 15- or 2-min preincubation) increased the pHirr. The baseline [Ca(2+)](i) was 103 ± 2 nM (n = 58). After 1 min of aldosterone preincubation, there was a transient and dose-dependent increase in [Ca(2+)](i) and after 6-min preincubation there was a new increase in [Ca(2+)](i) that persisted after 1 h. Spironolactone [mineralocorticoid (MR) antagonist], actinomycin D, or cycloheximide did not affect the effects of aldosterone (15- or 2-min preincubation) on pHirr and on [Ca(2+)](i) but inhibited the effects of aldosterone (1-h preincubation) on these parameters. RU 486 [glucocorticoid (GR) antagonist] and dimethyl-BAPTA (Ca(2+) chelator) prevented the effect of aldosterone on both parameters. The data indicate a genomic (1 h, via MR) and a nongenomic action (15 or 2 min, probably via GR) on the H(+)-ATPase and on [Ca(2+)](i). The results are compatible with stimulation of the H(+)-ATPase by increases in [Ca(2+)](i) (at 10(-12)-10(-6) M aldosterone) and inhibition of the H(+)-ATPase by decreases in [Ca(2+)](i) (at 10(-12) or 10(-6) M aldosterone plus RU 486).
authors.affiliation: Department of Basic Sciences, Faculdade de Zootecnia e Engenharia de Alimentos, Campus of Pirassununga, Instituto de Ciências Biomédicas, University of São Paulo, São Paulo, Brazil.
authors.forename: D C A
authors.initials: DC
authors.lastname: Leite-Dellova
authors.forename: G
authors.initials: G
authors.lastname: Malnic
authors.forename: M
authors.initials: M
authors.lastname: Mello-Aires
mesh_terms: D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006863:Hydrogen-Ion Concentration; D007687:Kidney Tubules, Proximal / Q000378:metabolism*; D008297:Male; D023421:Models, Animal; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000494:pharmacology
chemical_list: D000450:Aldosterone; D012964:Sodium; D006180:Proton-Translocating ATPases; D002118:Calcium