Secretion of alpha-tocopherol in VLDL is decreased by dietary protein insufficiency in young growing rats

The concentrations of alpha -tocopherol in plasma and most peripheral tissu es were shown previously to be low in young growing rats fed a low protein diet. To examine the secretion rates of VLDL alpha -tocopherol and triglyce rides, and lipoprotein lipase activity, weanling rats were fed a low protei n (LP, 8 g/100 g lactalbumin) or a normal protein (NP, 20 g/100 g lactalbum in) diet for 6 wk. The absolute secretion rate of VLDL triglyceride (mu mol /h) of the LP group was not significantly different from that of the NP gro up (P > 0.05), but was significantly higher (P < 0.05) when expressed relat ive to body weight [<mu>mol/(h.kg)]. The secretion rates of VLDL alpha -toc opherol were significantly lower (P < 0.05) in the LP group than in the NP group. The activities of hepatic lipase, lipoprotein lipase and total hepar in-releasable lipase in plasma of the LP group were only 50-60% those of th e NP group (P < 0.05). The results demonstrated that the secretion rate of VLDL alpha -tocopherol and activities of lipases in postheparin plasma were significantly lower in rats fed a low protein diet. Thus, the redistributi on of alpha -tocopherol from liver to peripheral tissues appears to have be en impaired by dietary protein insufficiency.