Influence of synthetic somatostatin upon growth hormone release from perifused rat pituitaries.
Basal release of pre-labeled, stored tritiated rat growth hormone ([3H]rGH) from perfused rat pituitary explants is a constant fraction of pituitary [LH]rGH content. Synthetic somatostatin (SRIF) inhibits the release of pre-labeled, stored [3H]rGH in a dose-dependent fashion. Prolonged exposure to SRIF results in an immediate and continuous inhibition of [3H]rGH release. In the in vitro perifusion system, the maximal inhibition, which is achieved with 25 nM SRIF, results in a rate of [3H]rGH release which is 30 to 40 per cent of basal release. Pulses of SRIF produce inhibition of [3H]rGH release followed by rebound release after withdrawal of SRIF. When the time of exposure to SRIF is held constant, both the SRIF-induced inhibition and the rebound release of [3H]rGH are dose-dependent. A similar progressive response is seen when a constant SRIF concentration is pulsed for variable periods of time. There is no net inhibition of [3H]rGH release by pulses of SRIF.
D000818:Animals; D013006:Growth Hormone / Q000378:metabolism*; D006728:Hormones / Q000494:pharmacology; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D010902:Pituitary Gland / Q000378:metabolism*; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D051381:Rats; D013004:Somatostatin / Q000494:pharmacology*
D006728:Hormones; D013004:Somatostatin; D013006:Growth Hormone