Stereospecific modulation of the calcium channel in human erythrocytes by cholesterol and its oxidized derivatives

• Published in: Biochemical journal Vol. 227; no. 1; pp. 105 - 112
• Main Authors: Neyses, L, Locher, R, Stimpel, M, Streuli, R, Vetter, W
• Format: Journal Article
• Language: English
• Published: England 01-04-1985
• Subjects: calcium; Calcium - blood; Calcium Channel Blockers - pharmacology; cholesterol; Cholesterol - analogs & derivatives; Cholesterol - pharmacology; erythrocytes; Erythrocytes - drug effects; Erythrocytes - metabolism; Humans; Ion Channels - drug effects; Ion Channels - metabolism; Kinetics; man; Molecular Conformation; Nifedipine - analogs & derivatives; Nifedipine - pharmacology; Nitrendipine
• ISSN: 0264-6021; 1470-8728
• DOI: 10.1042/bj2270105

To study the effect of cholesterol and its pathophysiologically important oxidized derivatives (OSC) on the calcium entry channel, the human red blood cell was used as a model system. The calcium ejecting adenosinetriphosphatase (ATPase) was inhibited by vanadate. The cells were loaded with OSC at concentrations between 1.25 X 10(-5) and 25 X 10(-5) mol/l. 22-Hydroxycholesterol, cholestan-3 beta,5 alpha,6 beta-triol, 5 alpha-cholestan-3 beta-ol,3 beta,5 alpha-dihydroxycholestan-6-one and 3 beta-hydroxy-5 alpha-cholestan-7-one stimulated 45Ca2+ influx by up to almost 90%, whereas 25-hydroxycholesterol, 7 beta-hydroxycholesterol, 20 alpha-hydroxycholesterol and 7-oxocholesterol inhibited influx by up to 75%. Both stimulation and inhibition were dependent on the amount of OSC incorporated into the membrane. More than 90% of the total modification of calcium influx by OSC was accounted for by an influence on the nitrendipine-inhibitable part of influx. Enrichment of cholesterol in the membrane greatly stimulated, and cholesterol depletion inhibited, Ca2+ influx. These results demonstrate that cholesterol and its oxidized derivatives are able to modulate the calcium channel in human red blood cells in a highly stereospecific manner.