Increased blood pressure and changes in membrane lipids associated with chronic ethanol treatment of rats

1. Changes in membrane fluidity have been proposed to contribute to the pathogenesis of ethanol-induced hypertension possibly through changes in membrane lipid patterns, but reports are inconsistent. 2. In a controlled trial we documented ethanol-induced changes in blood pressure and composition of membrane lipids in ethanol-fed rats. 3. Systolic blood pressure increased significantly in the ethanol-treated rats (9.3 mmHg, s.e.m. 2.9) compared with the control group (-1.3 mmHg, s.e.m. 2.6). Mean cholesterol content in red cell membranes did not differ significantly between ethanol-fed and control rats. Phospholipids of aorta, red cells and kidney showed a significant decrease in the polyunsaturated to saturated fatty acid ratio, while membrane phospholipids from the heart showed a significant increase in the polyunsaturated to saturated fatty acid ratio with ethanol treatment. 4. In univariate regression blood pressure was significantly negatively related to levels of arachidonic acid in the kidney (P = 0.0013) and to linoleic acid in the aorta (P = 0.0341) and red cells (P = 0.0289). Blood pressure was not significantly related to fatty acids in the heart nor to membrane cholesterol or phospholipids. 5. Differences in fatty acid composition of phospholipids between controls and ethanol-fed rats are consistent with altered membrane fluidity. Altered membrane function is a potential mechanism involved in ethanol-induced hypertension.