In-vitro stimulation on the rat epitrochlearis muscle. II. Effects of catecholamines and nutrients on protein degradation and amino acid metabolism.
The influence of catecholamines and branched-chain amino acids (BCAA) plus insulin on protein degradation and amino acid metabolism was investigated in isolated and electrically stimulated rat epitrochlearis muscles. 10(-7) M adrenaline significantly increased the total amount of muscle tyrosine during 40 min of stimulation with 50 Hz (I s min 1) pulse trains. On the other hand, BCAA + insulin at normal and five times normal plasma concentrations had no effect on muscle tyrosine. Muscle 3- methylhistidine was not influenced by any of the treatments. Muscle release and content of aspartate, alanine, glutamate and glutamine showed individual response characteristics to catecholamines and BCAA + insulin. The data indicate that adrenaline can induce an increased total protein degradation in rat fast muscle during acute contractions in vitro and, furthermore, that BCAA + insulin does not retard protein breakdown during acute muscle contraction.
Nie
Z T
ZT
Department of Physiology III Karolinska Institute, Stockholm, Sweden.
Lisjö
S
S
Astrand
P O
PO
Henriksson
J
J
D000596:Amino Acids / Q000378:metabolism*; D000597:Amino Acids, Branched-Chain / Q000494:pharmacology*; D000818:Animals; D002395:Catecholamines / Q000494:pharmacology*; D004558:Electric Stimulation; D004837:Epinephrine / Q000494:pharmacology; D006811:Humerus; D066298:In Vitro Techniques; D007328:Insulin / Q000494:pharmacology*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009132:Muscles / Q000378:metabolism*; D009638:Norepinephrine / Q000494:pharmacology; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains
D000596:Amino Acids; D000597:Amino Acids, Branched-Chain; D002395:Catecholamines; D007328:Insulin; D011506:Proteins; D009638:Norepinephrine; D004837:Epinephrine