title: Opiate nerves mediate feline pyloric response to intraduodenal amino acids.
abstract: Intraluminal pressures and myoelectric activity were recorded from the feline antrum, pylorus, and duodenum in response to intraduodenal amino acid solutions. Mixed amino acids (0.02 mg/ml, 3.0 ml) increased the amplitude of pyloric contractions (59.7 +/- 7.9 mmHg) and pyloric spike activity (73.7 +/- 6.8% of slow waves with spike activity) compared with a saline control (P less than 0.001). The selectivity of these responses was determined with specific amino acids. L-Tryptophan (10 or 40 mM) produced a response similar to the mixed amino acid response, while L-phenylalanine or L-glycine (10 or 40 mM) had no effect. Intra-arterial tetrodotoxin, intraluminal ethyl aminobenzoate, or intravenous naloxone (1.0 mg/kg) abolished the pyloric responses to amino acids (P less than 0.02). Bilateral cervical vagotomy had no effect. Cholecystokinin octapeptide (CCK-OP) produced dose-dependent increases in the amplitude of pyloric contractions and in pyloric spike activity. The ED50 dose of CCK-OP (1.0 microgram/kg iv) gave an increase in pyloric pressure of 155.6 +/- 49.9 mmHg and in spike activity of 77.7 +/- 9.4%, similar to mixed amino acids or tryptophan. These effects of CCK-OP were not antagonized, however, by a dose of naloxone (1.0 mg/kg) that blocked the maximal pyloric response to leucine-enkephalin. We concluded intraduodenal mixed amino acids or tryptophan increase phasic, spike-dependent pyloric contractions in the cat via nonvagal, naloxone-sensitive neural pathways, phenylalanine, a structurally similar essential amino acid, had no effect on the feline gastroduodenal junction, and the pyloric responses to exogenous CCK-OP are mediated by pathways distinct from the responses to tryptophan or mixed amino acids.
mesh_terms: D000596:Amino Acids / Q000494:pharmacology*; D000818:Animals; D002415:Cats; D004386:Duodenum / Q000378:metabolism*; D004723:Endorphins / Q000502:physiology; D005769:Gastrointestinal Motility; D009270:Naloxone / Q000494:pharmacology; D009434:Neural Pathways / Q000187:drug effects / Q000502:physiology; D010649:Phenylalanine / Q000494:pharmacology; D011708:Pylorus / Q000294:innervation* / Q000502:physiology; D012844:Sincalide / Q000494:pharmacology; D013268:Stimulation, Chemical; D014364:Tryptophan / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D004723:Endorphins; D009270:Naloxone; D010649:Phenylalanine; D014364:Tryptophan; D012844:Sincalide