Cholesterol and myocardial membrane function.
The incorporation of cholesterol into phospholipid membranes changes the physical properties of the membranes, such as their phase transition, fluidity and homogeneity. In cholesterol-containing phospholipid membranes, integral proteins are surrounded by "annular" phospholipids which exclude cholesterol. Cellular cholesterol is supplied by circulating low-density lipoproteins, and by intracellular de novo synthesis. Cholesterol removal is predominantly handled by circulating high-density lipoproteins. In cardiomyopathic hamsters, myocardial membranes (sarcolemma, mitochondria, sarcoplasmic reticulum) have an increased cholesterol content. In ischaemic myocardium, cholesterol content of sarcolemma fell and that of mitochondria rose. Apparently, cholesterol is redistributed within the ischaemic heart cell. Phospholipids are degraded in sarcolemma, mitochondria and sarcoplasmic reticulum of ischaemic heart cells, probably by activation of phospholipases present in these membrane systems.
van der Laarse
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Department of Cardiology, University Hospital Leiden, The Netherlands.
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D003327:Coronary Disease / Q000378:metabolism; D006801:Humans; D008563:Membrane Lipids / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism
D008563:Membrane Lipids; D010743:Phospholipids; D002784:Cholesterol