Age-related variations in jejunum and distal colon contractile response to thyrotropin-releasing hormone in vitro.
The effects of thyrotropin-releasing hormone (TRH) on the contractile activity of the proximal jejunum and distal colon of 3-, 7-, 14-, 21-, 28-, 50-day-old and adult male Sprague-Dawley rats were examined. Longitudinal segments were mounted in force displacement transducers and bathed in oxygenated, buffered Krebs' solution. In the proximal jejunum TRH 10(-6) M produced a tetrodotoxin (TTX)-sensitive tension increase in 3- to 14-day-old rats and a TTX-resistant biphasic response in older rats. TRH 10(-6) M produced a transient tension in the distal colon of rats less than or equal to 21 days old. Incubation with TRH 10(-6) M for 30 min increased responsiveness to acetylcholine 10(-7) M in approximately 50% of tissues studied. Direct and indirect effects of TRH are developmentally determined.
Heitkemper
M M
MM
Department of Physiological Nursing, University of Washington, Seattle.
Bond
E F
EF
D000109:Acetylcholine / Q000494:pharmacology*; D000375:Aging; D000818:Animals; D003106:Colon / Q000187:drug effects / Q000254:growth & development*; D005260:Female; D007583:Jejunum / Q000187:drug effects / Q000254:growth & development*; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D013779:Tetrodotoxin; D013973:Thyrotropin-Releasing Hormone; D000109:Acetylcholine