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.