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.