Lysine Deficiency and Carnitine in Male and Female Rats

Abstract

This study continues investigations from this laboratory on the question of the severity of carnitine deficiency in rats fed a 20% wheat gluten diet limiting in lysine in which carnitine synthesis is demanded. Under these nutritional conditions, male weanling rats over a 78 day life span grew poorly, had moderately decreased carnitine in the plasma, heart and skeletal muscle (75–85% of controls), markedly decreased carnitine in the epididymis (less than 50% of controls), but elevated carnitine in the liver. Male rats which were lysine deficient at birth and were fed the lysine deficient diet for 78 days were severely stunted in growth; but the carnitine status of these rats was not markedly changed from rats lysine deficient only since weaning. Normal female rats had only about half as much carnitine in the plasma as normal male rats. On the other hand, female rats which were lysine deficient at birth and were fed the lysine deficient diet for 78 days had plasma levels about the same as male rats made lysine deficient at birth; but such severe lysine deficiency had no significant effect on depressing carnitine levels in the tissues studied. It was concluded that with the exception of the epididymal findings, a severe lysine deficiency in the rat results in only a minor reduction of carnitine in the plasma, heart, and skeletal muscle. Such findings were rationalized in terms of present knowledge of the dietary control of lysine metabolism by lysine in the rat.