Objective: The objective of this study was to validate the use of impedance for measurement of antral contractions and to determine the relationship between food-induced changes in gastric motility and satiation.
Research Methods and Procedures: In Experiment 1, three dogs were implanted with an antral strain gauge and bipolar electrodes for measurement of local tissue impedance. Impedance and strain gauge recordings were obtained simultaneously during antral contractions to correlate impedance changes with contractile events. In Experiment 2, seven dogs were implanted with two pairs of gastric electrodes for simultaneous recording of slow wave activity and impedance. The changes in the rate of slow waves and of antral contractions assessed by impedance during food intake were characterized.
Results: Variations in strain gauge amplitude were highly correlated with changes in antral impedance (R2: 0.70 to 0.82, p < 0.05). In Experiment 2, slow wave rate was significantly reduced after food intake and reached a nadir at satiation (5.0 ± 0.3 vs. 3.8 ± 0.5 events/min, p < 0.001). Likewise, the amplitude of antral contractions assessed by variations in impedance was significantly increased after food intake, peaking at satiation (5.3 ± 1.4 vs. 12.2 ± 4.3 Ohms, p < 0.01).
Discussion: Measurement of impedance is a reliable tool for assessing gastric contractility. Food ingestion significantly reduces slow wave rate and enhances antral contractions. Peak changes in these two variables occur at the time of satiation. Electrical measurements of both slow waves and impedance may be used to estimate gastric motility and satiation.