The slow wave does not propagate across the gastroduodenal junction in the isolated feline preparation

Detailed spatial analysis of the propagation of individual slow waves was performed in the isolated gastroduodenal preparation of the cat. Use was made of a system that allowed the simultaneous recordings from 240 extracellular electrodes, which were positioned across the gastroduodenal region. Reconstructions of the spread of propagation (n = 31) revealed that (a) the antral slow wave never propagated into the duodenum but was blocked at the pyloric ring, (b) the duodenal slow wave did not activate the antral tissue, and (c) a quiescent zone in which no slow waves could be recorded was always present at the most proximal part of the duodenum immediately distal to the pyloric ring. Furthermore, phase density distributions of duodenal cycles revealed that antral activity had no influence on the rate of discharge of duodenal pacemakers. Light microscopic study of sections of the duodenum close to the pyloric ring and further away did not show any structural differences between the quiescent zone and the active areas. In conclusion, slow waves do not propagate across the gastroduodenal junction in the isolated feline preparation and therefore do not seem to play a role in the electro-mechanical integration between the stomach and the duodenum.