It has been shown that the lipid composition of plasma membrane can be modified in vivo by dietary fat. It has also been observed that an increase in the cholesterol content of plasma membranes results in decreased activities of ATPases. In the present study, we evaluated the changes in the activities of ATPases from erythrocytes, hepatocytes, and kidney cortex caused by cholesterol-rich diet in rats and subsequently examined the role of vitamin E administration on the cholesterol-induced effects in these tissues. Administration of hypercholesterolemic diet to the rats for 4.5 months, significantly decreased membrane Na(+)-K(+)-ATPase and Ca+2-ATPase activities in comparison to the controls in all tissues studied. Vitamin E supplementation to the hypercholesterolemic rats led to a recovery in membrane ATPase activities. In conclusion, vitamin E supplementation to the rats provided protection against hypercholesterolemic diet-induced impairment of membrane-bound ATPases.