Effect of dietary fat on sodium transport and sodium-lithium countertransport in rat erythrocytes and thymocytes.

Two groups of normotensive Sprague-Dawley rats were fed high fat diets (40% of calories derived from fat). One group received a diet high in polyunsaturated fat (corn oil 45% polyunsaturated), and the other a diet high in saturated fat (coconut oil). Growth rates were the same in both groups. Sodium transport was measured in isolated thymocytes from both groups. The rats fed the diet high in polyunsaturated fat had lower sodium efflux rate constants than those fed the diet high in saturated fat. The reduction was almost entirely confined to the ouabain-sensitive portion of sodium efflux. Sodium-lithium countertransport in isolated thymocytes and erythrocytes was the same for both groups.