Effect of dietary methionine level on anserine and carnosine contents in the gastrocnemius muscle of rat.

Anserine and carnosine in the muscle of growing rats were measured to explore the effect of dietary methionine. Carnosine was reduced in the gastrocnemius muscle of rats fed on a methionine-free diet. After refeeding on methionine for one week, carnosine in the muscle approached to the normal level. In contrast, anserine increased in the muscle of rats fed on a methionine-free diet. Anserine also increased in the gastrocnemius muscle of rats fed on a methionine-excess diet, whereas carnosine did not vary. Npi-Methylhistidine was detected in the muscle of rats fed on a methionine-excess diet. Moreover, Npi-methylhistindine and Ntau-methylhistine in the urine increased in the rats fed on both methionine-excess and methionine-free diets. Carnosine in the gastrocnemius muscle was not affected by a ethionine diet nor by a orotic acid diet which induced fatty liver. However, anserine increased in the muscle of rats fed on a ethionine diet.