Determinants of occurrence and volume of transpyloric flow during gastric emptying of liquids in dogs - Importance of vagal input

The precise factors and their relative contributions that lead to individua l flow pulses across the pylorus during liquid gastric emptying remain uncl ear. Our objective was to determine the factors leading to individual flow pulses, their relative contributions and the role of the vagus nerve in the ir modulation. Proximal gastric tone had a strong positive correlation with the volume of the corresponding transpyloric flow pulse whereas pyloric to ne had an inverse correlation. Antral contractions were associated with the presence but not the volume of the pulse. Acute vagal blockade retarded em ptying via loss of proximal gastric tone and increased outflow resistance a nd loss of propagating antral pressure waves. In conclusion, the major dete rminants of the volume of pulsatile transpyloric flow are proximal gastric and pyloric tone. The vagus nerve plays a key role in regulating both proxi mal gastric and pyloric tone as well as moderating propagating antral contr actions.