title: Half-life and metabolic clearance rate of recombinant-derived chicken growth hormone and purified turkey growth hormone in intact and hypophysectomized turkeys.
abstract: The half-life and metabolic clearance rate (MCR) of natural turkey growth hormone (tGH) were compared with those of recombinant-derived chicken growth hormone (rcGH) in intact and hypophysectomized (hypox) turkey poults at 8 and 13 wk of age. The hypox poults used were all hypophysectomized at 8 wk of age. The purpose of the experiment was to determine whether the source of growth hormone (GH) or the physiological changes associated with hypophysectomy might affect the disappearance of the hormone from the circulation and, hence, alter the biological response of the bird to exogenous GH. The mean half-life of GH in the growing turkey was 12.88 +/- .54 (SE) min. The source of GH had no effect on half-life, and GH half-life did not vary significantly between poults sampled at 8 and 13 wk. Hypophysectomy significantly (P less than .01) increased the half-life of administered GH from 11.21 +/- .50 min in intact poults to 14.70 +/- .84 min in hypox poults. The MCR of GH in hypox poults 2 days following hypophysectomy was markedly lower than that of intact birds (1.08 versus 2.95 mL/min; P less than .001). The GH clearance in hypox birds increased during the 5 wk following hypophysectomy but still remained somewhat lower than that of intact birds (2.55 versus 3.00 mL/min; P = .06). The MCR of GH did not change in intact birds between 8 and 13 wk of age, and the MCR of rcGH and tGH did not differ.(ABSTRACT TRUNCATED AT 250 WORDS)
authors: Livestock and Poultry Sciences Institute, Agricultural Research Service, Beltsville, Maryland 20705.
authors: J A
authors: JA
authors: Proudman
authors: H
authors: H
authors: Opel
mesh_terms: D000818:Animals; D002645:Chickens; D005260:Female; D013006:Growth Hormone / Q000493:pharmacokinetics*; D006207:Half-Life; D007016:Hypophysectomy / Q000662:veterinary*; D011994:Recombinant Proteins / Q000493:pharmacokinetics; D014422:Turkeys / Q000378:metabolism* / Q000601:surgery
chemical_list: D011994:Recombinant Proteins; D013006:Growth Hormone