Aldosterone biosynthesis in extraadrenal tissues

Objective To determine whether extraadrenal tissues synthesize aldosterone in addition to vascular tissue and brain. Methods Ex vivo kidney perfusion was performed in normal Wistar rats. ACEI pretreated and adrenalectomized rats prior to the perfusion experiment. Aft er equilibration for 30 minutes, 120 mi of perfusate was collected and subj ected to reverse-phase HPLC and then aldosterone was measured by RIA. By RT -PCR and Southern blot the expression of aldosterone synthase gene-CYP11B2 mRNA was studied in both kidney tissue and cultured renal tubular epithelia l cell, lung and liver tissues. In situ hybridization was used to identify the cell types of liver and lung expressing CYP11B2 mRNA. Results Production of aldosterone in the kidney perfusate was not changed i n adrenalectomized rats although it was decreased in the group pretreated w ith ACEI perindopril. By R-T-PCR and Southern blot the expression of CYP11B 2 mRNA was demonstrated in both kidney tissue and cultured renal tubular ep ithelial cell. We have also identified CYP11B2 mRNA expression in liver and lung of rats. In situ hybridization showed that CYP11B2 mRNA was localized in the endoplasm of liver fat-storing cell (Ito cells) and type II: alveol ar cells of lung. Conclusions These studies prove that kidney, liver and lung are able to pro duce aldosterone.