Abstract
Our aim was to study a role of nitrergic input in gastric relaxation in conscious dogs. Proximal gastric motor responses to mechanical distension and chemical stimulation (a lipid meal orally) were evaluated by electronic barostat. Effect of NG-monomethyl-L-arginine acetate (L-NMMA, 5 mg/kg) on these responses was studied. When mechanical stimulation was applied, we observed steep linear increases in intragastric pressure up to about 6 mmHg, then continued to increase gradually, and could be increased still further upon the addition of L-NMMA. Oral application of a lipid led to a prompt fall in intragastric pressure (gastric receptive relaxation; GRR). Lipid treatment also led to a considerable increase in gastric volume (means ± S.D., 150.0 ± 50.2 ml), this was followed by a plateau phase and a gradual return to baseline levels. Neither GRR nor the associated increase in gastric volume (167.6 ± 53.0 ml) was sensitive to treatment with L-NMMA. Our conclusion is that nitrergic input is necessary for mechanically induced gastric relaxation, but not for either GRR or chemically-induced gastric relaxation in conscious dogs.
