In vitro effects of growth hormone on protein synthesis and amino acid transport in the rat diaphragm after acute hypophysectomy.
The effects of growth hormone (GH) in vitro on phenylalanine-14C incorporation to assess protein synthesis and on alpha-aminoisobutyric-1-3H accumulation to measure amino acid transport in the diaphragm muscle of the rat were investigated 2, 6 and 24 h after hypophysectomy or sham-operation. In hypophysectomized animals protein synthesis was depressed. GH in vitro was without effect 2 h after hypophysectomy but stimulated protein synthesis 6 and 24 h after the operation. Six hours after hypophysectomy amino acid transport was enhanced and further stimulated by GH. After 24 h amino acid transport was depressed but was stimulated to normal levels by GH. Six hours after sham-operation protein synthesis was depressed, but was stimulated by GH. After 24 h protein synthesis was normalized and GH was without effect. GH did not influence amino acid transport after sham-operation. Plasma levels of GH were undetectable after hypophysectomy, markedly depressed 2 and 6 h after sham-operation, but normal after 24 h. It is concluded that tissue responsiveness to GH develops a few hours after hypophysectomy.
D000596:Amino Acids / Q000378:metabolism*; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003964:Diaphragm / Q000378:metabolism; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000494:pharmacology*; D007016:Hypophysectomy; D009124:Muscle Proteins / Q000096:biosynthesis*; D009132:Muscles / Q000378:metabolism*; D051381:Rats; D013997:Time Factors
D000596:Amino Acids; D001786:Blood Glucose; D009124:Muscle Proteins; D013006:Growth Hormone