Dietary cholesterol affects Na+ -K+ pump function in rabbit cardiac myocytes

• Published in: The American journal of physiology Vol. 272; no. 4; pp. H1680 - H1689
• Main Authors: Gray, D.F, Hansen, P.S, Doohan, M.M, Hool, L.C, Rasmussen, H.H
• Format: Journal Article
• Language: English
• Published: United States 01.04.1997
• Subjects: Animals; Cells, Cultured; Cholesterol - blood; Cholesterol, Dietary - pharmacology; diet-related diseases; Heart - drug effects; Heart - physiology; human nutrition; Male; Membrane Potentials - drug effects; Myocardium - enzymology; Ouabain - pharmacology; Patch-Clamp Techniques; Rabbits; Sodium-Potassium-Exchanging ATPase - drug effects; Sodium-Potassium-Exchanging ATPase - metabolism; Time Factors
• ISSN: 0002-9513; 2163-5773
• DOI: 10.1152/ajpheart.1997.272.4.H1680

Alterations in membrane cholesterol induced in vitro can alter Na+-K+ pump function. Because dietary cholesterol can influence membrane cholesterol in vivo, we examined if dietary cholesterol is a determinant of Na+-K+ pump function. Rabbits were fed cholesterol-supplemented diets for 1-4 wk. Cardiac myocytes were then isolated, and Na+-K+ pump currents (Ip) were measured using the whole cell patch-clamp technique. When the Na concentration in the patch pipettes ([Na]pip) was 10 mM, a modest diet-induced increase in serum cholesterol was associated with stimulation of Ip; large increases in serum cholesterol were associated with inhibition. There was no effect of modest or large increases in serum cholesterol on Ip when [Na]pip was 80 mM. The [Na]pip-Ip relationship determined using seven different levels of [Na]pip from 0 to 80 mM indicated that a modest increase in serum cholesterol increased the apparent affinity of the pump for cytoplasmic Na+. In contrast, dietary cholesterol had no effect on the apparent affinity of the pump for extracellular K+. We conclude that cholesterol intake influences the sarcolemmal Na+-K+ pump. This may have clinical implications for cardiovascular function.