Figure 8. Effect of superfusing the IMG with maxadilan (A), PACAP27 (B) and VIP (C) on intracellularly recorded electrical activity of IMG neurones (lower traces) and intraluminal pressure of the attached colonic segment (upper traces).

Note that application of maxadilan and PACAP27 evoked neuronal activation that either strongly depressed or abolished colonic contractions. In 2 out of 11 experiments, application of PACAP27 also caused relaxation (decrease in resting pressure) of the colon segment (not shown). Application of VIP, which also activated the IMG neurones, abolished colonic motility in 2 out of 9 experiments. In the other 7 experiments VIP either only slightly depressed or did not cause any changes in the amplitude and frequency of colonic contractions (not shown in this figure). All agents were used at 500 nm, diluted in NKS.