34 Senso‐reflexory control of the gastric myoelectrical activity – effect of oral exposure to a sweet or a bitter taste on a multichannel electrogastrogram

Aim:  To examine the effect of sensory stimulation with a sweet or a bitter taste on the interdigestive gastric myoelectrical activity (GMA) in humans. Methods:  Eighteen healthy subjects (10F, 8M) underwent on two separate days four-channel electrogastrographic recordings comprising three consecutive 35 min periods: (i) basal fasted, (ii) a stimulation epoch while a subject was chewing an agar cube soaked with a taste-delivering substance (saccharose for the sweet taste, quinine hydrochloride for the bitter taste), (iii) a post-stimulatory (recovery) epoch. An electrocardiogram was simultaneously registered for the purpose of the heart rate variability (HRV) analysis. Results:  Exposure to the sweet taste brought about an increase in the power of the high frequency (HF: 0.15–0.4 Hz) band of the power spectrum-analyzed HRV data. The bitter taste had no effect on the HRV. During the stimulation and the recovery epoch a statistically significant augmentation in the relative time share of tachy- and bradygastria within the multichannel electrogastrogram was found either with the sweet or the bitter taste. Whereas no any other modifications of the GMA were elicited by the sweet taste, the exposure to the bitter taste resulted in a statistically significant decrease in the relative time share of normogastria, a decline in the dominant frequency and the dominant power of the gastric slow waves, as well as a reduction in the percentage of the slow wave coupling. Conclusions:  (i) Exposure to the sweet taste elicits a vagal arousal expressed by an increase in the HF power, whereas the bitter taste does not affect the equilibrium between the parasympathetic and the sympathetic component of the autonomous nervous system; (ii) The increased relative time contribution of tachy- and bradygastria within the electrogastrogram during both the stimulation and the recovery epoch should be considered an unspecific phenomenon because it accompanied stimulation either with the sweet or the bitter taste; (iii) The inhibitory effect of the bitter taste on the GMA, reflected by a diminution in the dominant frequency and the dominant power of the gastric slow waves, as well as their reduced coupling, may be indicative of an evolutionary archetype of a warning reaction of the human (mammalian) organism towards this taste.