Chemical Assay of Phospholipid Renin Preinhibitor in Canine and Human Blood

Abstract

A phospholipid previously shown to be converted to a lysophospholipid renin inhibitor has been demonstrated in the plasma and red cells of man and the dog. This inhibitor precursor, designated preinhibitor, is chromatographically identical to the compound previously isolated from kidneys of dogs and hogs. A method for its quantitative measurement in plasma and red cells is presented. Normal dogs tested so far have an average of 119.6 µg of preinhibitor phospholipid/ml of blood; 16.3 µg of this is in the plasma. These concentrations are constant (in red cells even increased) 48 hr after bilateral nephrectomy. To assess the physiological importance of preinhibitor, it may be necessary to measure its active lyso derivative as well as the lipase(s) most directly involved in maintaining blood levels of these two phospholipids.