Smoking-Induced Alterations in Platelet Membrane Fluidity and Na+/K+-ATPase Activity in Chronic Cigarette Smokers

Aim: Cigarette smoking is a recognized risk factor for cardiovascular diseases and has been implicated in the pathogenesis of atherosclerosis. Platelet adhesiveness and aggregation increases as a result of smoking. Cigarette smoking modifies haemostatic parameters via thrombosis with a consequently higher rate of cardiovascular events, but smoking-induced alterations of platelet membrane fluidity and other changes have not been studied. Methods: Thirty experimental and control subjects (mean age 35 +/- 8) were selected for the study. Experimental subjects had smoked 10 +/- 2 cigarettes per day for 7-10 years. The plasma lipid profile, platelet carbonyls, sulfhydryl groups, Na+/K+-ATPase activity, fluidity using a fluorescent probe 1,6-diphenyl-1,3,5-hexatriene (DPH), total cholesterol and phospholipids as well individual phospholipids were determined. Results: Increases in the platelet membrane cholesterol phospholipid (C/P) ratio, phosphotidylethanolamine, phosphotidylserine with decreased phosphotidylcholine, Na+/K+-ATPase activityactivity, fluidity and no significant change in phosphotidylinositol and sphingomylein, as well as increases in plasma total cholesterol, LDL-cholesterol, protein carbonyls with decreased HDL-cholesterol and sulfhydryl groups were observed in cigarette smokers. Platelet membrane total phospholipids were positively correlated with plasma LDL-cholesterol (r = 0.568) and VLDL-cholesterol (r = 0.614) in cigarette smokers. Conclusions: Increased plasma LDL-cholesterol, VLDL-cholesterol and total cholesterol might have resulted in the increased C/P ratio and decreased platelet membrane fluidity of cigarette smokers.