Transgenic rats, termed TGR(mREN2)27, have been generated carrying the mouse ren-2 renin gene. As intended the gene was expressed highly within the adrenal gland offering the opportunity to study the intraadrenal renin-angiotensin system in vivo. Concomitantly with increased adrenal renin activity, the production of adrenocortical steroids are elevated and the regulation of aldosterone production is impaired in TGR(mREN2)27. Furthermore, the transgenic rats develop severe sodium dependent hypertension. Since kidney and plasma renin concentrations and plasma angiotensins are low in the transgenic model, those factors cannot account for the altered regulation of aldosterone production. Instead the experiments with TGR(mREN2)27 demonstrate the functional role of the local adrenal renin-angiotensin system.