Studies on hypoxic dyslipidaemia. Effect of lipid modulating drugs

Haemorrhagic anaemia, exposure to altitude and depression of cell respiration are known to increase plasma triglyceride and cholesterol levels. The common triggering mechanism in all 3 instances is oxygen deficiency but mode of action is not known. The present study was intended to investigate whether lipid lowering drugs clofibrate or gemfibrozil could counteract such hypoxic dyslipidaemia in rats induced by altitude exposure. It was unexpectedly found that in normal rats gemfibrozil elevated plasma total cholesterol with an increase in the HDL-cholesterol component whereas clofibrate caused a rise in LDL-cholesterol. Nicotinic acid had no consistent effect. In hypoxia control rats showed an increase in cholesterol and triglyceride level. Both gemfibrozil and clofibrate prevented the rise of triglycerides. Total cholesterol fell in rats treated either with gemfibrozil or clofibrate during altitude exposure, indicating that neither natural nor gemfibrozil-augmented hyper-HDL-aemia could be maintained during oxygen deficiency.