Effect of converting enzyme inhibitors on prostaglandin synthesis by isolated glomeruli and aortic strips from rats.

In addition to their effect on angiotensin and bradykinin metabolism, converting enzyme inhibitors (CEI) may also alter prostaglandin (PG) synthesis. We therefore examined two CEI, SQ 14,225 (captopril) and SQ 20,881, for their in vitro effect on PG synthesis by glomeruli and aortic strips from rats. Glomeruli incubated in test tubes produced predominantly PGE2 and PGF2 alpha. Both CEI selectively stimulated PGE2 synthesis with maximal effects at 25 microM. During superfusion of glomeruli with captopril (25 microM) synthesis of PGE2 increased 5- to 10-fold and that of 6-keto-PGF1 alpha doubled. No significant change in PGF2 alpha or thromboxane B2 occurred. This effect of CEI was independent of angiotensin or bradykinin. In contrast captopril had no effect on PG synthesis by aortic strips, which produced predominantly prostacyclin assayed as 6-keto-PGR1 alpha and little PGE2 and PGF2 alpha. These results demonstrate that CEI can directly stimulate PG synthesis in glomeruli. This additional mechanism of action of CEI may require reinterpretation of the role of angiotensin based on results obtained with CEI.