Decrease in Enkephalinase a Number in Kidney Membranes from Hypercholesterolemic and Hypertensive Rats

Abstract

The variation of enkephalinase A number on the hypertensive and hypercholesterolemia rats kidney membranes is studied using the [³H]-acetorphan, a potent inhibitor of enkephalinase A to label the protease in rat kidney. The binding of [³H]-acetorphan to kidney membrane determined in vitro with both equilibrium and kinetic methods is saturable and reversible involving a single class of sites with a dissociation constant of 4-5.3 nM. The [³H]-acetorphan binding capacity is identical, Bmax ∼ 51 pmoles per mg of proteins, for kidney membranes from Sprague Dawley and Wistar Kyoto rats. In contrast, the enkephalinase A number is decreased in the pathological states studied: 20 % for hypertensive rats and 50% for hypercholesterolemic rats. Such pharmacological results provide a great deal of information about the modification appeared in the metabolism of peptidic substrates of enkephalinase A in hypercholesterolemia and hypertension.