ウサギ胃平滑筋の各種作用薬に対する収縮反応の発達

抄録

We used muscle strips from rabbit proximal stomach to study developmental changes in response to putative agonists. Strips from neonatal (1 day old) and weanling (11 weeks old) rabbits were stimulated by agonists and the contractions were recorded. Maximal stress and ED₅₀ were calculated from the dose response curves. Maximal stress increased with age for bethanechol, high extracellular K⁺, substance P, substance K, and neuromedin K, but not for serotonin, cholecystokinin-octapeptide, or neurotensin. Bombesin stimulated larger contractions in neonates. Gastrin, motilin and morphine had no effect at either age. ED₅₀'s for substance P and for serotonin in neonates were 24 to 800 times less than those seen in weanlings.
These data suggest that developmental changes in gastrointestinal motility seen in the neonatal period might be due to modulation of muscle responses to agonists.