SYNTHESIS OF CORTICOSTERONE IN THE VASCULAR WALL

Extra-adrenal steroid 21-hydroxylation and 11 beta-hydroxylation occur in a variety of human tissues. This study was undertaken to determine a whether the rat mesenteric artery produces corticosterone and to de monstrate the CYP11B1 mRNA in the vascular tissue. Isolated rat mesent eric arteries were perfused with Krebs-Ringer solution for 1 h. The pe rfusate was collected and chromatographed in a reverse-phase HPLC syst em. The fraction corresponding to synthetic corticosterone was collect ed and analyzed by mass spectrometry. The concentration of corticoster one in the perfusate from the adrenalectomized rats was measured using radioimmunoassay after separation with the HPLC system. The mass spec tra of synthetic corticosterone was identical with corticosterone isol ated from the perfusate of the rat mesenteric arteries. The radioactiv e peak of corticosterone nas detected in the perfusate after perfusing the mesenteric arten with Krebs-Ringer solution containing [C-14]-pre gnenolone, The expression of CYP11B1, 11B2, and 11A mRNA was detected in the mesenteric artery using a RT-PCR. The production of corticoster one in the vascular wall was increased in the adrenalectomized rats co mpared with that of the controls. This study shows that the rat mesent eric artery produces corcicosterone, and the corticosterone synthase i s existed in the vasculature.