Myocardial Na+-K+-ATPase activity and [3H]ouabain binding sites in hypertensive rats.
Na+-K+-ATPase activity and [3H]ouabain binding were studied in cardiac ventricles of single wrapped kidney and DOCA-NaCl hypertensive rats. It was found that the total Na+-K+-ATPase activity decreased in the DOCA-NaCl and kidney wrapped hypertensive rats. The decrease of enzyme activity in DOCA-NaCl hypertensive rats was due to extracellular fluid expansion induced by NaCl loading, as DOCA itself had no effect on the enzyme. All these alterations were specific for Na+-K+-ATPase, since Mg2+-ATPase and 5'-nucleotidase activities were unaffected. Binding studies with [3H]ouabain showed that the decrease in Na+-K+-ATPase activity was due to a reduction in the number of binding sites for ouabain rather than to a change of binding affinity. The reduced myocardial Na+-K+-ATPase activity observed in these two types of low renin hypertension, coupled with the observation of reduced vascular Na+ pump activity by others, suggests a common underlying defect in the cardiovascular Na+-K+ transport system of these hypertensive rats.
Chen
C C
CC
Pharmacological Institute, College of Medicine, National Taiwan University, Taipei, R.O.C.
Shiau
S Y
SY
D015720:5'-Nucleotidase / Q000378:metabolism; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D006321:Heart / Q000187:drug effects; D006973:Hypertension / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D008861:Microsomes / Q000201:enzymology / Q000378:metabolism; D009206:Myocardium / Q000201:enzymology*; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D011955:Receptors, Drug / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D011955:Receptors, Drug; C028996:cardiac glycoside receptors; D015720:5'-Nucleotidase; D000254:Sodium-Potassium-Exchanging ATPase