Reference : The cholesterol content of the human erythrocyte influences calcium influx through th...
Scientific journals : Article
Human health sciences : Cardiovascular & respiratory systems
The cholesterol content of the human erythrocyte influences calcium influx through the channel.
Locher, R. [> >]
Neyses, Ludwig mailto [University of Luxembourg > Research Office]
Stimpel, M. [> >]
Kuffer, B. [> >]
Vetter, W. [> >]
Biochemical and biophysical research communications
[en] Calcium/blood ; Cholesterol/blood ; Erythrocytes/analysis ; Humans ; Ion Channels/metabolism ; Kinetics ; Liposomes/metabolism ; Nifedipine/analogs & derivatives/pharmacology ; Nitrendipine ; Phosphatidylcholines/blood ; Time Factors
[en] In order to study the influence of the cholesterol content on the calcium entry channel, the human red blood cell was used as a model system. The cholesterol to lecithin ratio (C/L ratio) of the membrane was modified experimentally by incubating the cells (15h, 25 degrees) with liposomes of defined C/L ratios. Subsequently, net 45Calcium-influx into the cell was measured by inhibiting the Ca-ejecting ATPase with vanadate. Additionally, the use of nitrendipine, a potent calcium channel inhibitor, during incubation allowed the determination of Ca-influx through the calcium channel. A positive correlation between the 45Ca++-influx and the molar C/L ratio of the membrane was found over a wide C/L range. A molar C/L ratio of 1.4 in the membrane increased calcium influx by 150 % compared to controls (molar C/L ratio = 0.8, calcium influx rate = 100 %), while a molar C/L ratio at less than 0.75 decreased calcium influx by 50 %. We conclude, that the cholesterol content of the membrane greatly influences the calcium channel and thus plays a pivotal role for the availability of calcium as a second messenger. These findings may provide a link between high plasma cholesterol and the development of atherosclerosis as well as enhanced platelet aggregability.

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