SHEEP TESTICULAR AND EPIDIDYMAL ANGIOTENSIN-CONVERTING ENZYME - INHIBITIONS BY CAPTOPRIL, LISINOPRIL AND ENALAPRIL

Inhibition of angiotensin converting enzyme(ACE) in presence of captop ril(C), lisinopril(L) and enalapril(E) were investigated in testis and epididymis of sheep using Hip-His-Leu as substrate. Captopril, lisino pril and enalapril were competitive inhibitors of the enzyme from both tissues. Differences in the I-50 and K-i values using these three inh ibitors reflects the affinities of these inhibitors for the ACE. I;I a ddition, :he relative potencies of captopril, lisinopril and enalapril were different for testicular ACE(C > L > E) and epididymal ACE(L > C > E). This observation suggests differences between the active sites of the testicular and epididymal ACE which may reflect on their functi ons in vivo.