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 < 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 < 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 μg/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 1) intraduodenal mixed amino acids or tryptophan increase phasic, spike-dependent pyloric contractions in the cat via nonvagal, naloxone-sensitive neural pathways, 2) phenylalanine, a structurally similar essential amino acid, had no effect on the feline gastroduodenal junction, and 3) the pyloric responses to exogenous CCK-OP are mediated by pathways distinct from the responses to tryptophan or mixed amino acids.
|Original language||English (US)|
|Journal||American Journal of Physiology - Gastrointestinal and Liver Physiology|
|State||Published - 1985|
All Science Journal Classification (ASJC) codes
- Physiology (medical)