References of "Kuffer, B."
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See detail[Divisible tablets--source of error in therapeutic drug dosages].
Stimpel, M.; Vetter, H.; Kuffer, B. et al

in Schweizerische Rundschau für Medizin Praxis (1985), 74(5), 84-6

Detailed reference viewed: 172 (1 UL)
Peer Reviewed
See detailCholesterol and its oxidized derivatives modulate the calcium channel in human red blood cells.
Neyses, Ludwig UL; Stimpel, M.; Locher, R. et al

in Journal of Hypertension. Supplement) (1984), 2(3), 489-92

The human red blood cell was used as a model system in order to study the effect of cholesterol and its medically important oxidized derivatives (OSC = oxidized sterol compounds) on the calcium entry ... [more ▼]

The human red blood cell was used as a model system in order to study the effect of cholesterol and its medically important oxidized derivatives (OSC = oxidized sterol compounds) on the calcium entry channel. The calcium-ejecting adenosine triphosphatase (ATPase) was inhibited by vanadate and the influx of 45Ca2-into the cells measured. The cells were loaded with OSC at concentrations between 0.075 and 1.5 micrograms OSC/10(7) cells. Two classes of OSC could be distinguished: one stimulating Ca2+ influx dose-dependently by almost 100% at maximum concentrations, the other inhibiting it dose-dependently by up to 80%. The calcium channel blocker nitrendipine inhibited influx by 70% at 15 microM. More than 90% of the total stimulation or inhibition was accounted for by an influence on the nitrendipine-inhibitable part of influx, i.e. the calcium channel. Cholesterol (incorporated using liposomes) had a stimulatory (+288%), cholesterol depletion an inhibitory effect on calcium influx (-18%). These results demonstrate that cholesterol and its oxidized derivatives modulate the calcium channel in a highly stereospecific manner and provide new insights into the mechanism of action and the atherogenic effect of these compounds. [less ▲]

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See detailThe cholesterol content of the human erythrocyte influences calcium influx through the channel.
Locher, R.; Neyses, Ludwig UL; Stimpel, M. et al

in Biochemical and biophysical research communications (1984), 124(3), 822-8

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 ... [more ▼]

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. [less ▲]

Detailed reference viewed: 241 (0 UL)