Alanine release by rat diaphragm muscle in vitro is stimulated by glutamate, valine, leucine and glucose. The stimulation by glutamate and valine (but not leucine) is inhibited by 3-mercaptopicolinate. These results suggest a metabolic route involving phosphoenolpyruvate carboxykinase which directs amino acid carbon skeletons towards pyruvate synthesis for alanine formation.

Rats were overnourished during suckling by litter-size manipulation in order to investigate the possible association of overfeeding in infancy with the development of obesity in later life. Rats were raised in litters of 4, 10 and 16 corresponding to overfeeding, normal feeding and underfeeding during the suckling period. From 6-19 days post partum, growth rates of pups from different litter sizes were significantly different (4 greater than 10 greater than 16). Differences in mean body weights between the groups continued to increase after weaning when all groups were allowed access to diet ad libitum and the significant weight difference between overfed and normally fed rats persisted into adult life in both males and females. Overfed animals showed modifications in the development of activities of a number of hepatic enzymes involved in lipid and carbohydrate metabolism. In later life (20 weeks) neonatally overnourished rats exhibited alterations in hepatic enzyme activities that reflected an increased capacity for lipid synthesis by the liver. "Supernourishment" of neonatal rats (by intubation with glucose of animals in small litters), accelerated the appearance of some of these alterations. These studies show that the pattern of early infant nutrition can profoundly influence the activities of liver enzymes in later, adult life.

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Table 1. Eflect of exercise on rat muscle protein synthesis and intramuscular free 3-methylhistidine All rats were 100-159g body wt. and had been provided with food ad libitum. Experiments conducted with living rats were performed with single doses of ('4Cltyrosine and IMe-'4Clmethionine, and a time course of precursor specific activity was constructed by killing rats at intervals. Exercised rats ran on a treadmill at 0.8m.p.h., 5% grade. [Results are from Bates er al. (1980).1 Synthesis rates obtained in perfused rat hindquarter were calculated from the incorporation of I l4C1tyrosine into mixed muscle protein from perfusate containing plasma concentrations of amino acids (except 5 x tyrosine), 4.5% bovine serum albumin, rejuvenated human erythrocytes and 100 punits of insulin/ml. Isometric contraction of the muscles of the hindquarter was induced by electrical stimulation of the femoral and sciatic nerves in their lumbar course by trains of stimuli (looms trains, 1 train/% IOOHz, 0.05ms stimuli). IResults are from M. J. Rennie (unpublished work).] All values are means & S.D. (a) Living rats Rested (n = 18) Exercised (40min) (n = 18) Post-exercise (40min) (n = 18) (b) Perfused rat hindquarter Rest (90min) (n = 12) Electrical muscle stimulation (30min) (n = 8) Post-muscle stimulation (90min) (n = 6) Mixed muscle protein synthesis (%/day) 14.02 1.8 9. 1 f 1.7 11.5 f 1.8 13.6+ 1.4 10.2 f 1.5 16.1 f 2.1 Muscle free Actin synthesis 3-methylhistidine (%/day) (nmol/g) 15.424.5 7.0 f 0.8 3.6 2 0.6 5.Of 1.0 4.6 f 0.5 6.0 1 .O 775-780 pp. 1286-1287, C. V.