Effect of increased calcium intake on cardiac and vascular Na(+)-K(+)-ATPase activity in oral contraceptive-treated female Sprague-Dawley rats.
The present study aimed at investigating the influence of increased dietary calcium on Na(+)-K(+)-ATPase activity in heart and aorta of female Sprague-Dawley rats treated with oral contraceptive (OC) steroids. Rats were grouped as control (CR), OC-treated and OC+calcium-treated. OC-treated and OC+calcium-treated received a combination of OC steriods (ethinyloestradiol and norgestrel; ig). OC+calcium-treated rats were fed with 2.5% calcium diet, while OC-treated and CR groups were fed on 0.9% calcium diet. The activity of Na(+)-K(+)-ATPase in heart and aorta was significantly lower in OC-treated rats than those in the other groups. OC treatment caused significant increase in plasma glucose and significant decrease in plasma K+ as compared to control group. Decrease in Na(+)-K(+)-ATPase activity and plasma K+ was abrogated by increased calcium intake, while increase in plasma glucose was not normalized by calcium supplementation. Plasma levels of Na+, lipid peroxidation index and ascorbic acid were comparable among the three groups. These results showed that OC treatment could lead to impaired activity of cardiac and vascular Na(+)-K(+)-ATPase, possibly due to reduced plasma K+ level and these effects could be abolished by high calcium diet.
Olatunji
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Department of Physiology and Biochemistry, College of Medicine, University of Ilorin, P.M.B. 1515, Ilorin, Nigeria. tunjilaw04@yahoo.com
Soladoye
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D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D001786:Blood Glucose / Q000032:analysis / Q000187:drug effects; D001808:Blood Vessels / Q000187:drug effects / Q000201:enzymology*; D002136:Calcium, Dietary / Q000494:pharmacology*; D003276:Contraceptives, Oral / Q000494:pharmacology*; D005260:Female; D006321:Heart / Q000187:drug effects; D008315:Malondialdehyde / Q000097:blood; D009206:Myocardium / Q000201:enzymology*; D018384:Oxidative Stress / Q000187:drug effects; D011188:Potassium / Q000097:blood; D051381:Rats; D017207:Rats, Sprague-Dawley; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*
D001786:Blood Glucose; D002136:Calcium, Dietary; D003276:Contraceptives, Oral; D008315:Malondialdehyde; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium