Mechanics and neuropeptide responses of feline pylorus and gastric muscle in vitro.
Mechanical properties and neuropeptide responses were compared for feline pyloric and gastric muscle under isometric conditions in vitro. Total tension in antral circular muscle (0.699 +/- 0.003 kg/cm2) was less than in corpus circular (1.597 +/- 0.007 kg/cm2) or longitudinal muscle from the lesser and greater curvatures (1.256 +/- 0.009 and 1.253 +/- 0.007 kg/cm2, n greater than or equal to 55, P less than 0.05). The components of tension at optimal length were similar for all gastric muscles (P greater than 0.1). The pylorus maintained less total tension (0.335 +/- 0.003 kg/cm2) and a greater component of resting tension (75.6%) than gastric muscle (P less than 0.01). Substance P, cholecystokinin-8 (CCK-8), and neurotensin varied in potency and efficacy in circular muscle of the antrum, corpus, and inferior portion of the pyloric ring. Longitudinal muscle and the superior portion of pylorus responded poorly if at all to neuropeptides. Substance P- but not CCK-8- or neurotensin-induced contractions of gastric muscle were reduced by tetrodotoxin (TTX) and atropine (P less than 0.05). Substance P-induced pyloric contractions were TTX sensitive (P less than 0.05) but were unaffected by atropine. We concluded that 1) length-tension properties of gastric muscle are similar and distinct from the pylorus and that 2) neuropeptide efficacy varies regionally within the feline stomach and within the pylorus.
Merlo
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A
Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania 19140.
Cohen
S
S
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002415:Cats; D066298:In Vitro Techniques; D009119:Muscle Contraction / Q000187:drug effects; D009496:Neurotensin / Q000494:pharmacology*; D011708:Pylorus / Q000502:physiology; D012844:Sincalide / Q000494:pharmacology*; D013270:Stomach / Q000187:drug effects / Q000502:physiology*; D013373:Substance P / Q000494:pharmacology*; D013779:Tetrodotoxin / Q000494:pharmacology
D013373:Substance P; D009496:Neurotensin; D013779:Tetrodotoxin; D012844:Sincalide; D000109:Acetylcholine