Decreased myocardial Na+K+ATPase activity in rats with reduced renal mass-saline hypertension.

Abstract

Inhibition of cardiovascular Na,K-pump activity has been shown to promote an increase in the contractile activity of myocardial and vascular smooth muscle and a consequent rise in blood pressure (BP). It has also been shown that vascular Na,K-pump activity and myocardial Na+K+ATPase activity [the energy source for active sodium (Na) and potassium (K) transport] are decreased in rats with various forms of low renin hypertension including rats with reduced renal mass-saline (RRM-saline) hypertension. In the present study, left ventricular Na+K+ATPase activity from rats with RRM-saline hypertension was found to be decreased in membranes prepared by two independent methods: deoxycholate, sodium iodide (Nal)-treated microsomal fractions (method 1) and membranes prepared by the hypotonic, lithium bromide (LiBr) method (method 2). Relative to RRM normotensive control rats which drank distilled water, myocardial Na+K+ATPase activity from RRM-saline drinking rats was decreased by 18.2% in membranes prepared by method 1 and 33.6% in membranes prepared by method 2. The apparent affinities of Na+K+ATPase for K and for ouabain were unaltered relative to controls in membranes prepared from these hypertensive rats by method 1, and the sialic acid content and 5'-nucleotidase activity (two putative sarcolemmal markers) were unaltered in membranes from the hypertensive rats, prepared by methods 1 and 2 respectively. The Mg2+ATPase activity of membranes prepared by method 1 was increased in the RRM-saline hypertensive rats but because it was not increased in membranes prepared by method 2 the former observation does not appear to be of any pathophysiological importance. In other experiments, hypertension was reversed in RRM-saline hypertensive rats by restricting their salt intake (substitution of distilled water for drinking).(ABSTRACT TRUNCATED AT 250 WORDS)

• Authors: D L Clough, S J Huot, M B Pamnani, F J Haddy
• Journal: Journal of hypertension (J Hypertens) Vol. 3 Issue 6 Pg. 583-9 (Dec 1985) ISSN: 0263-6352 [Print] England
• PMID: 3003189 (Publication Type: Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Sodium Chloride
• Ouabain
• Sodium-Potassium-Exchanging ATPase

Topics

• Animals
• Blood Pressure
• Body Weight
• Cell Membrane (enzymology)
• Hypertension, Renal (enzymology, physiopathology)
• Kinetics
• Male
• Myocardium (enzymology)
• Ouabain (pharmacology)
• Rats
• Rats, Inbred Strains
• Sodium Chloride
• Sodium-Potassium-Exchanging ATPase (metabolism)