ISSN:
1435-1803
Keywords:
Hypercholesterolemia
;
membrane lipid
;
Na+−K+-ATPase
;
ouabain receptor
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract Objectives The purpose of this study was to explore the effect of high dietary cholesterol on the lipid composition, Na+−K+-ATPase activity and ouabain receptor property of the myocardial sarcolemma. Methods Male New Zealand white rabbits were fed with standard chow or standard chow supplemented with 0.5% (w/w) cholesterol and 10% (w/w) coconut oil to induce hypercholesterolemia. After 8 weeks, the rabbits were sacrificed; a myocardial sarcolemma fraction was then prepared from the left ventricular myocardium and analyzed for lipid composition. Assay of Na+−K+-ATPase activity and3H-ouabain binding studies were performed in the myocardial sarcolemma from the control and cholesterol-fed rabbits. Results The cholesterol content, but not the phospholipid content, of the sarcolemma was significantly greater in the cholesterol-fed group, thus, resulting in an increased cholesterol/phospholipid molar ratio in the cholesterol-fed group. In addition, a decrease in Na+−K+-ATPase activity was also found in this group. The decrease in Na+−K+-ATPase activity was selective, since the Mg++-ATPase and 5′-nucleotidase activities remained unchanged. In the3H-ouabain binding study, a decrease in the number of maximum binding sites, but not the binding affinity, for3H-ouabain was foundie the cholesterol-fed group. Conclusions High dietary cholesterol induces higher levels of cholesterol not only in the plasma, but also in the myocardial sarcolemma. These changes result in decreased myocardial Na+−K+-ATPase activity mediated by a reduction in the maximum number of binding sites for ouabain but not a change in binding affinity.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00803751
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