Regulation of renin angiotensins by gonadotropic hormones in cultured murine Leydig tumor cells. Release of angiotensin but not renin.

Renin and angiotensins coexist in various tissues. The mode of control of the extrarenal renin-angiotensin system is not clear. Whether it is renin or angiotensin that is secreted has not been identified. We have investigated gonadotropin-dependent synthesis and subsequent release of the components of the intracellular renin-angiotensin system in a cloned and cultured mouse Leydig tumor cell line (MA-10). Treatment of cultured Leydig cells with bovine luteinizing hormone (bLH, 100 ng/ml) or human chorionic gonadotropin (hCG, 25 ng/ml) resulted in greater than 150- and 40- fold increased formation of angiotensin I and angiotensin II. In cells incubated with bLH or hCG, the majority of AII (up to 90%) was found in the culture medium while most of angiotensin I (greater than 85%) was in the cell lysate. Treatment with gonadotropic hormones (bLH/ hCG) increased renin 35- to 40-fold. Renin activity was confined mainly in the cell lysate even after the stimulation by gonadotropins, and only 1-2% of the total renin activity was detectable in culture medium. These results were interpreted that, in these transformed cells, hormonally-induced renin functions to generate angiotensin I within the Leydig cell and it is the angiotensins which are secreted.