The half-life (t( 1/2 )) of disappearance of endogenous GH from serum was studied using physiological effectors to stimulate and then suppress GH release. GH secretion was stimulated by a single iv injection of GHRH, followed 45 min later by an iv bolus dose and then a 2.5-h infusion of somatostatin (SRIH) to suppress further release. The in vivo t( 1/2 ) of GH in seven men was calculated from serum GH concentrations measured at frequent intervals after beginning the SRIH infusion. The mean t( 1/2 ) of endogenous GH was 18.9 ± 0.8 (± SE) min by monoexponential analysis and 3.5 ± 0.7 and 20.7 ± 0.7 min by biexponential fitting. In these normal men, the decline in GH concentrations after GHRH and SRIH administration was similar to that after the administration of GHRH alone, which yielded at t( 1/2 ) of 20.3 ± 1.9 min. We conclude that the physiological kinetics of endogenous GH removal/disappearance can be estimated in vivo in man using GHRH with or without SRIH infusion.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Clinical Endocrinology and Metabolism|
|State||Published - 1989|
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism