Evidence for a Na-K-ATPase-inhibitor in erythrocytes of patients with essential hypertension.
ATPase activities were determined in haemolysed and dialysed erythrocytes and in haemoglobin-free membranes of twenty patients with essential hypertension and twenty normotensive controls. Ouabain-sensitive ATPase (Na-K-ATPase) activity of haemolysate but not that of membranes was decreased in hypertensives whereas ouabain-insensitive ATPase (Mg-ATPase + some residual Ca-ATPase) activity was increased in both enzyme preparations when measurements were preformed in the absence of Ca2+-chelating substances. In haemolysed erythrocytes ouabain-sensitivity as a percentage of total ATPase activity was a good discriminator between both groups and may be a possible marker for essential hypertension. The decreased activity of Na-K-ATPase in haemolysate is apparently due to a non dialysable inhibitor of Na-K-ATPase which is either tightly bound to the erythrocyte membrane or dissolved in the cytoplasm. Following haemolysis with subsequent centrifugation the Na-K-ATPase inhibitor is removed, at least in part, and thus differences in Na-K-ATPase activity demonstrable in haemolysed and dialysed erythrocytes are no longer apparent in haemoglobin-free membranes.
D000293:Adolescent; D000328:Adult; D002469:Cell Separation / Q000379:methods; D003956:Dialysis; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism*; D006461:Hemolysis; D006801:Humans; D006973:Hypertension / Q000097:blood*; D066298:In Vitro Techniques; D008297:Male; D008875:Middle Aged; D010042:Ouabain / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000097:blood
D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase