Effect of CCK-8 on myoelectrical activity of the gastrointestinal tract in the conscious miniature pig

Origin, propagation and regional characteristics of porcine gastric slow wave activity determined by high-resolution mapping

BACKGROUND

The pig is a popular model for gastric electrophysiology studies. However, its normal baseline gastric activity has not been well characterized. High-resolution (HR) mapping has recently enabled an accurate description of human and canine gastric slow wave activity, and was employed here to define porcine gastric slow wave activity.

METHODS

Fasted pigs underwent HR mapping following anesthesia and laparotomy. Flexible printed-circuit-board arrays were used (160-192 electrodes; spacing 7.62 mm). Anterior and posterior surfaces were mapped simultaneously. Activation times, velocities, amplitudes and frequencies were calculated, and regional differences evaluated.

KEY RESULTS

Mean slow wave frequency was 3.22 ± 0.23 cpm. Slow waves propagated isotropically from the pacemaker site (greater curvature, mid-fundus). Pacemaker activity was of higher velocity (13.3 ± 1.0 mm s(-1)) and greater amplitude (1.3 ± 0.2 mV) than distal fundal activity (9.0 ± 0.6 mm s(-1), 0.9 ± 0.1 mV; P < 0.05). Velocities and amplitudes were similar in the distal fundus, proximal corpus (8.4 ± 0.8 mm s(-1), 1.0 ± 0.1 mV), distal corpus (8.3 ± 0.8 mm s(-1), 0.9 ± 0.2 mV) and antrum (6.8 ± 0.6 mm s(-1), 1.1 ± 0.2 mV). Activity was continuous across the anterior and posterior gastric surfaces.

CONCLUSIONS & INFERENCES

This study has quantified normal porcine gastric slow wave activity at HR during anesthesia and laparotomy. The pacemaker region was associated with high-amplitude, high-velocity slow wave activity compared to the activity in the rest of the stomach. The increase in distal antral slow wave velocity and amplitude previously described in canines and humans is not observed in the pig. Investigators should be aware of these inter-species differences.

Effect of cisapride on myoelectrical activity of the gastrointestinal tract in the conscious miniature pig

In conscious miniature pigs with electrodes implanted in the wall of the antrum pylori, duodenum, jejunum, ileum and caecum, the influence of intravenous injection of cisapride, 0.5 and 1 mg/kg, on gastrointestinal myoelectrical activity, was examined. Cisapride, 1 mg/kg, induced a delayed and sustained increase in antral myoelectrical activity. The studied intestinal segments were rather insensitive to the stimulating effect of the benzamide, since only the jejunum and the caecum revealed an increase in myoelectrical activity with the higher dose studied.