Converting enzyme, kininase and angiotensinase of renal and intestinal brush border

Abstract

Kinins and angiotensins affect renal and intestinal function and are rapidly converted and/or inactivated in the renal proximal tubule and intestinal tract by converting enzyme, kininases and angiotensinases of the brush border. Converting enzyme accounts for only 40% of intestinal kininases activity. Thus inhibition of converting enzyme by captopril, while completely inhibiting intestinal angiotensin II generation, may only partially inhibit kinin inactivation. In the kidney, however, converting enzyme accounts for the majority of renal kininase activity. Thus the effect of captopril on inhibition of renal angiotensin II formation and kinin inactivation may be similar. Using monospecific antibody to purified converting enzyme and techniques of rocket and fused-rocket immunoelectrophoresis, renal and intestinal converting enzyme can be detected, quantitated and partially characterized. The immunologic localization of renal and intestinal converting enzyme is identical to its enzymatic localization. Immunoelectrophoretic analysis of membrane-bound peptidases is a valuable approach to investigating membrane metabolism of vasoactive peptides.