Altered Na+-K+-ATPase, cell Na+ and lipid profiles in canine arterial wall with chronic cigarette smoking

Abstract

1. We evaluated the influence of cigarette smoking on arterial wall membranes, using Na+-K+-ATPase activity, free cholesterol (FC) and phospholipid (PL) contents as indices of membrane structural and functional integrity. 2. Segments of aorta, carotid and femoral arteries were obtained from normal dogs (controls) and dogs subjected to chronic cigarette smoking for 2 yr (12 cigarettes a day). 3. Na+-K+-ATPase activity was assessed in segments of carotid and femoral arteries using a ouabain-sensitive 86Rb uptake procedure for intact tissues. 4. Free cholesterol and phospholipids were separated, identified, and quantitated from extracts of aortic samples by means of two dimensional thin-layer chromatography. 5. Na+-K+-ATPase activity was reduced in the smoker group in both carotid and femoral arteries. This reduced enzyme activity was accompanied by a rise in cell Na+ levels at both arterial sites. 6. Aortic FC was elevated and the PL profile was altered in the smoker group; as a result, phosphatidylcholine was reduced, whereas lysophosphatidylcholine, phosphatidic acid, and cardiolipin were elevated. 7. Phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine and sphingolipid levels were unchanged. In addition, the FC/PL ratio was increased in the smokers. 8. Taken together, the changes in Na+-K+-ATPase activity, FC/PL ratio and phospholipid profiles observed are consistent with the hypothesis that chronic cigarette smoking causes a reorganization of the phospholipid bilayer in the smooth-muscle cell membrane of the arterial wall.