ANGIOTENSIN-II RECEPTORS, AT(1) AND AT(2) IN THE RAT EPIDIDYMIS IMMUNOCYTOCHEMICAL AND ELECTROPHYSIOLOGICAL STUDIES

Previous work from our laboratory has provided evidence for the presen ce of a tissue renin-angiotensin system in the rat epididymis. In the current investigation, the regional localization of angiotensin II rec eptors, type I (AT(1)) and type II (AT(2)) was studied immunocytochemi cally using specific anti-peptide antibodies against the second extrac ellular loops of AT(1) and AT(2) receptors, and pharmacologically usin g specific receptor antagonists in conjunction with the short-circuit current technique, The immunocytochemical results showed that AT(1) an d AT(2) immunoreactivities were predominantly localized in the basal r egion of the epididymal epithelium. Electrophysiological studies using the short-circuit current technique demonstrated a stimulatory effect of basolaterally applied angiotensin II on the epididymal electrogeni c ion transport. This effect was inhibitable by the addition of AT(1) antagonist, losartan but not by AT(2) antagonist, PD123177, indicating a functional role of AT(1) in epididymal electrolyte transport. The p resent finding suggests that angiotensin II receptors may play an impo rtant role in the regulation of epididymal function.