Effect of Dopamine or Dopamine Blocker on the Antral Motility in Isolated Perfused Rat Stomach
In isolated perfused rat stomach preparation, effects of dopamine; domperidone, a peripheral dopamine blocker; secretin; and cholecystokinin-octapeptide (CCK-OP) on the antral motility were studied. While the stomach was perfused with Krebs-Ringer (K-R) solution at a rate of 1.1 ml/min via celiac artery, motility was recorded through a open tip tube placed in the antrum which was connected to the Statham pressure transducer and Harvard peristaltic pump (0.03 ml/min). Gastric fluid was drained by a tube placed in the proximal duodenum. Peptides or drugs were infused through the celiac artery. Results: 1) Domperidone produced dose-dependent increases (r=0.68) in motility at doses of 0.08, 0.16, 0.32 and 0.64 μg, 2) Dopamine produced dose-dependent decreases in motility (r=0.76) at dose of 0.13, 0.25 and 0.5 μg which were reversed by domperidone, 0.32 pg, 3) Secretin inhibited the motility in a dose-dependent manner (r=0.49) at doses of 62.5, 125 and 250 pg which were also reversed by domperidone, 0.64 μg, 4) CCK-OP produced inhibition of motility at dose of 40 ng (p<0.025) which was also reversed by domperidone, 0.32 μg. In conclusion, local dopamine receptors in the rat stomach have an inhibitory effect on antral motility, while a peripheral dopamine blocker, domperidone, exerts a gastrotonic effect on spontaneous and inhibited antral motility by either secretin or CCK-OP. Thus, local dopamine receptors in the stomach appear to play a significant role on regulation of antral motility in physiological state.