The effect of age, mating and vasoligature on angiotensin I converting enzyme in rat testis and epididymis.

Angiotensin I converting enzyme was measured in testis, different sections of epididymis and vas deferens of rats with the analytical method of Piquilloud et al. In tissue specimens without a prior washout of seminal fluid the highest enzyme activity was found in the testis. The enzyme activity fell significantly towards the end of the excurrent ducts, suggesting that the enzyme is synthesized in the Sertoli cells of the testis, undergoes exocrine secretion and is partially inhibited during passage through the epididymis. This was supported by additional analyses of seminal fluid from rete testis and vas deferens. According to data obtained from various age groups, sexual stimulation due to mating and bilateral vasoligature, enzyme synthesis in the testis and enzyme inhibition in the epididymis seem to be under simultaneous (androgenic) control. Though the highest specific enzyme activity in the rat is located in the gonads, CE's enzyme substrate and the anatomical structures on which its reaction product is effective are not yet apparent.