Muscle and liver glycogen, protein, and triglyceride in the rat: effect of exercise and of the sympatho-adrenal system

TY - JOUR

T1 - Muscle and liver glycogen, protein, and triglyceride in the rat

T2 - effect of exercise and of the sympatho-adrenal system

AU - Richter, Erik

AU - Sonne, Bente

AU - Joensen Mikines, Kari

AU - Ploug, Thorkil

AU - Galbo, Henrik

PY - 1984

Y1 - 1984

N2 - We have previously found that during exercise net muscle glycogen breakdown is impaired in adrenodemedullated rats, as compared with controls. The present study was carried out to elucidate whether, in rats with deficiencies of the sympatho-adrenal system, diminished exercise-induced glycogenolysis in skeletal muscle was accompanied by increased breakdown of triglyceride and/or protein. Thus, the effect of exhausting swimming and of running on concentrations of glycogen, protein, and triglyceride in skeletal muscle and liver were studied in rats with and without deficiencies of the sympatho-adrenal system. In control rats, both swimming and running decreased the concentration of glycogen in fast-twitch red and slow-twitch red muscle whereas concentrations of protein and triglyceride did not decrease. In the liver, swimming depleted glycogen stores but protein and triglyceride concentrations did not decrease. In exercising rats, muscle glycogen breakdown was impaired by adrenodemedullation and restored by infusion of epinephrine. However, impaired glycogen breakdown during exercise was not accompanied by a significant net breakdown of protein or triglyceride. Surgical sympathectomy of the muscles did not influence muscle substrate concentrations. The results indicate that when glycogenolysis in exercising muscle is impeded by adrenodemedullation no compensatory increase in breakdown of triglyceride and protein in muscle or liver takes place. Thus, indirect evidence suggests that, in exercising adrenodemedullated rats, fatty acids from adipose tissue were burnt instead of muscle glycogen.

AB - We have previously found that during exercise net muscle glycogen breakdown is impaired in adrenodemedullated rats, as compared with controls. The present study was carried out to elucidate whether, in rats with deficiencies of the sympatho-adrenal system, diminished exercise-induced glycogenolysis in skeletal muscle was accompanied by increased breakdown of triglyceride and/or protein. Thus, the effect of exhausting swimming and of running on concentrations of glycogen, protein, and triglyceride in skeletal muscle and liver were studied in rats with and without deficiencies of the sympatho-adrenal system. In control rats, both swimming and running decreased the concentration of glycogen in fast-twitch red and slow-twitch red muscle whereas concentrations of protein and triglyceride did not decrease. In the liver, swimming depleted glycogen stores but protein and triglyceride concentrations did not decrease. In exercising rats, muscle glycogen breakdown was impaired by adrenodemedullation and restored by infusion of epinephrine. However, impaired glycogen breakdown during exercise was not accompanied by a significant net breakdown of protein or triglyceride. Surgical sympathectomy of the muscles did not influence muscle substrate concentrations. The results indicate that when glycogenolysis in exercising muscle is impeded by adrenodemedullation no compensatory increase in breakdown of triglyceride and protein in muscle or liver takes place. Thus, indirect evidence suggests that, in exercising adrenodemedullated rats, fatty acids from adipose tissue were burnt instead of muscle glycogen.

KW - Adrenal Medulla

KW - Animals

KW - Glycogen

KW - Liver Glycogen

KW - Male

KW - Muscle Proteins

KW - Muscles

KW - Physical Exertion

KW - Rats

KW - Rats, Inbred Strains

KW - Running

KW - Swimming

KW - Sympathetic Nervous System

KW - Triglycerides

U2 - 10.1007/BF01015225

DO - 10.1007/BF01015225

M3 - Journal article

C2 - 6539692

SN - 0301-5548

VL - 52

SP - 346

EP - 350

JO - European Journal of Applied Physiology and Occupational Physiology

JF - European Journal of Applied Physiology and Occupational Physiology

IS - 3

ER -