Effect of hyperinsulinemia and hyperaminoacidemia on muscle and liver protein synthesis in lactating goats

• Published in: The American journal of physiology Vol. 267; no. 6 Pt 1; p. E877
• Main Authors: Tauveron, I, Larbaud, D, Champredon, C, Debras, E, Tesseraud, S, Bayle, G, Bonnet, Y, Thiéblot, P, Grizard, J
• Format: Journal Article
• Language: English
• Published: United States 01.12.1994
• Subjects: acide amine; amino acids; Amino Acids - blood; aminoacidos; Animals; Blood Glucose - analysis; caprin; caprinos; Fatty Acids, Nonesterified - blood; foie; Goats; higado; insulin; Insulin - blood; insulina; insuline; lactacion; lactation; Lactation - metabolism; liver; Liver - metabolism; metabolic disorders; muscle; Muscle, Skeletal - metabolism; muscles; musculos; Protein Biosynthesis; protein synthesis; sintesis de proteinas; synthese proteique; trastornos metabolicos; trouble du metabolisme; valina; valine
• ISSN: 0002-9513; 2163-5773
• DOI: 10.1152/ajpendo.1994.267.6.e877

The experiment was carried out to clarify the roles of insulin and amino acids on protein synthesis in fed lactating goats (30 days postpartum). Protein synthesis in the liver and various skeletal muscles was assessed after an intravenous injection of a large dose of unlabeled valine containing a tracer dose of L-[2,3,4-3H]valine. The animals were divided into three groups. Group I was infused with insulin (1.7 micromole/min) for 2.5 h under glucose, potassium, and amino acid replacement. Group A was infused with an amino acid mixture to create stable hyperaminoacidemia for 2.5 h. Group C animals were controls. The fractional synthesis rates (FSR) were 31.5 +/- 2.2, 6.5 +/- 0.4,4.3 +/- 0.8,4.0 +/- 1.2,3.9 +/- 1.2, and 3.6 +/- 0.4%/day (SD) in liver, masseter, diaphragm, anconeus, semitendinosus, and longissimus dorsi, respectively, for group C. Neither hyperinsulinemis in group I nor hyperaminoacidemia in group A had an effect on FSR in the skeletal musdes. FSR in the liver was not affected by hyperinsulinemia but was stimulated by hyperaminoacidemia (+30%, P < 0.05). In contrast to previous experiments in which a labeled amino acid was constantly infused, this study revealed a stimulating effect of amino acids on protein synthesis in the liver but not in skeletal muscles. As previously observed in studies with the constant-infusion method, insulin had no effect on protein synthesis.