Action of growth hormone in vitro on the net uptake and incorporation in protein of amino acids in muscle from intact rabbits given protein-deficient diets.
1. Net amino acid uptake, and incorporation into protein have been measured in vitro in the presence and absence of porcine growth hromone (GH) in muscle from intact rabbits fed for 5 d on low-protein (LP), protein-free (PF) or control diets. 2. In muscle from control and LP animals GH had no effect on the net amino acid uptake but stimulate amino acid incorporation into protein, although this response was less in LP animals than in control animals. 3. In muscle of PF animals, GH stimulated both amino acid incorporation into protein and the net amino acid uptake, a type of response which also occurs in hypophysectomized animals. The magnitude of the effect of GH on the incorporation of amino acids into protein was reduced in muscle from PF animals. 4. The effect of GH on the net amino acid uptake in PF animals was completely blocked by cycloheximide; the uptake effect of GH in these animals was dependent therefore on de novo protein synthesis. 5. It is proprosed that in the adult the role of growth hormone in protein metabolism is to sustain cellular protein synthesis when there is a decrease in the level of substrate amino acids, similar to that which occurs during a short-term fast or when the dietary protein intake is inadequate.
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001834:Body Water / Q000032:analysis; D003513:Cycloheximide / Q000494:pharmacology; D003964:Diaphragm; D004044:Dietary Proteins; D005110:Extracellular Space / Q000032:analysis; D005260:Female; D013006:Growth Hormone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D008297:Male; D009124:Muscle Proteins / Q000096:biosynthesis*; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D011488:Protein Deficiency / Q000378:metabolism*; D011817:Rabbits; D013552:Swine
D000596:Amino Acids; D004044:Dietary Proteins; D009124:Muscle Proteins; D013006:Growth Hormone; D003513:Cycloheximide