[Relation between the electrical and mechanical activity of the stomach. In situ study of the anesthetized rat]

The relations between the electrical and mechanical activity of the corpus and the antrum have been studied by means of several microelectrodes and enterographic transducer under binocular control (X 5) in anaesthetized rats (pentobarbital Na, 4 mg/kg). The recording period starts from 30 min after the onset of anaesthesia. This time corresponds to the release of the post operative inhibitions. Several rhythms of slow components have been in evidence thanks to a long time constant (5 sec): the dominant component with his frequency 4.04 +/- 1.06 c/min (n = 302 values). This frequency increases (5.11 +/- 1.3 c/min) during the antropyloric evacuation. Other rhythmic components of smaller amplitude (less than 200 microV) and frequency ranging between 7-16 c/min have been seen in quiescent conditions. In contractile state, the incidence of such rhythms decreases. The weakest manifestations of mechanical activity consist of small rhythmic variations of volume, the frequency corresponding to the main gastric rhythm of 4.5 c/min; however any spiking activity is observed. The second step of activity is the peristalsis (speed: 1 mm/sec), the circular contractility is accompanied by small spikes (less than 200 microV) in short salves. The third step is marked by the antral contraction with an important volume of variation, spike bursts of greater amplitude and biphasic slow wave are recorded. The antral activity is followed by a break of the main rhythm activity during 20 sec. These activities appear as a result from a structuration of local oscillators of relatively high frequency, in this species.