Effects of cholic acid on blood pressure and production of vascular aldosterone and corticosterone

The aims of this study were to search for the role of cholic acid in the re gulation blood pressure of humans and rats and to investigate the effects o f cholic acid on the production of vascular aldosterone and corticosterone in rats. Levels of serum total bile acids were measured by an enzymic spect rophotometeric method in normal controls, patients with essential hypertens ion, and in Wistar and spontaneously hypertensive rats. Levels in essential hypertension (7.3 +/- 3.4 mu mol/l, n = 88) were higher than those of norm al subjects (4.9 +/- 3.3 mu mol/l, n = 86), and levels in SHR (13.9 +/- 3.8 mu mol/l, n = 11) were slightly increased, bur not significantly different from Wistar rats (10.4 +/- 5.1 mu mol/l, n = 12). Male Wistar rats receive d cholic acid 80 mg/kg/day, orally, for 30 days, and blood pressure was mon itored by a pressure transducer. Systolic blood pressure increased in Wista r rats treated with cholic acid compared to control rats. Mesenteric artery perfusion ex vivo was performed, and presser responses to norepinephrine w ere determined in Wistar rats. The presser responses to norepinephrine in m esenteric arteries treated with cholic acid were significantly increased. T he perfusate from the mesenteric arteries was collected and applied to a Se p-Pak C 18 cartridge column for reverse phase high performance liquid chrom atography, and levels of both aldosterone and corticosterone: were determin ed by radioimmunoassay. Levels of aldosterone were decreased bur those of c orticosterone increased in the perfusate from arteries treated with cholic acid. Reverse transcriptase polymerase chain reaction showed that cholic ac id inhibited the expression of 11 beta-HSD2 and CYP11B2 mRNA in mesenteric arteries. These results reveal that cholic acid is able to induce hypertens ion and provide evidence that cholic acid inhibits the transcription of bot h 11 beta-HSD2 and CYP11B2 in vasculature, leading to lower aldosterone and higher corticosterone production in vessels and increased vasoconstrictor responses to norepinephrine. (C) 1999 Elsevier Science Inc. All rights rese rved.