Effect of fasting, hypocaloric feeding, and refeeding on the energetics of stimulated rat muscle as assessed by nuclear magnetic resonance spectroscopy.

Abstract

A previous study suggested that muscles from hypocalorically fed rats were limited in their ability to rephosphorylate ADP. During muscle contraction hydrolysis of ATP results in an increase in phosphorus, free ADP, AGATp, and a reduction in phosphocreatine levels that is reversed during rest by rephosphorylation of ADP to ATP and the resynthesis of phosphocreatine by ATP. We therefore hypothesized that these changes would be restored more slowly during postcontraction rest in hypocalorically fed rats as compared with controls. We compared controls fed ad lib to 2-d fasted and hypocalorically fed rats, losing 20% of their weight. We also compared hypocalorically fed rats that had been refed ad lib for 7 d with agematched controls fed ad lib. The results showed that ATP, muscle pH, and total muscle creatine levels were not different in all groups. The raised phosphorus and AGATp levels and lower phosphocreatine /phosphorus ratio at the end of contraction changed more slowly during rest in the hypocaloric rats. These abnormalities were partially corrected by refeeding. The data taken as a whole support the concept of impaired rephosphorylation of ADP in malnourished muscle that is not completely restored by refeeding in stimulated muscle. (J. Clin.

Fast digestive, leucine‐rich, soluble milk proteins improve muscle protein anabolism, and mitochondrial function in undernourished old rats

“…mitochondrial proteins. Previous studies suggest that muscle cell energetics are altered by protein–energy restriction, showing altered mitochondrial function and slower rephosphorylation of ADP in the skeletal muscle of malnourished rats . Here, and in line with this observation, undernutrition reduced mitochondrial biogenesis and impaired the activity of the Krebs cycle and the activity and gene expression of the mitochondrial electron transport chain in muscle (complex II).…”

Comprehensive nutritional status in recently diagnosed patients with inflammatory bowel disease compared with population controls

“…It is known that corticosteroids therapy and also malnutrition may induce selective type IIb ®bre atrophy (Russell et al, 1983;van Balkom et al, 1994). Furthermore, malnutrition is associated with altered energy generation in the mitochondria (ie impaired rephosphorylation of ADP in the muscle) (Mijan de al Torre et al, 1993) and with relative loss of muscle creatine and phosphorus in relation to ATP (Thompson et al, 1998). Jeejeebhoy suggested that ATP generation in muscle may be abnormal despite normal body composition in these patients (Jeejeebhoy, 1998).…”

Intrauterine energetic malnutrition in rats: skeletal muscle changes in the 1st and 2nd generations

“…Animais jovens sub-metidos à desnutrição e à posterior recuperação nutricional mantêm o agravo prévio de ultra-estrutrura de mitocôndrias 44 e mantêm a limitação da refosforilação do ADP 45 . Esses fatos indicam persistência da disfunção mitocondrial, apesar da recuperação nutricional.…”