Influence of thymic fraction 5 on erythrocyte (Na+ + K+)-ATPase activity in hypercholesterolemic rabbits.

The effects of thymus fraction 5 injection on cholesterol, triglyceride and phospholipid levels in plasma and erythrocytes as well as on membrane-bound (Na+ + K+)-ATPase activity were investigated in rabbits fed a high-cholesterol diet for 3 months. While cholesterol feeding caused an increase in plasma and erythrocytes phospholipid levels, (Na+ + K+)-ATPase activity was found to be reduced. After high-cholesterol diet, the rabbits were given normal diet with or without thymosin F5 injections every other day for 21 days. Thymosin F5 treatment caused a significant decrease in plasma and erythrocyte phospholipid levels whereas membrane-bound (Na+ + K+)-ATPase activity was increased significantly. It is concluded that hypercholesterolemic lesions and the decreased erythrocyte ATPase activity may be eliminated by thymic extracts in rabbits.