Increase in the intestinal slow-wave frequency below the transection through electrical stimulation

Experiments are carried out on dogs with chronically implanted leading-off electrodes on both sides of the transection at the level of the proximal duodenum. A pair of stimulating electrodes are also implanted below the transection. Electrical stimulation with impulses synchronized with the slow waves generated by the segment proximal to the section (amplitude 3-7 V, delay 0.2 s and duration 0.5 s) as well as with periodic impulses (18-21 cpm, duration 0.2-0.5 s and amplitude 3-10 V) results in shortening of the period T of several slow waves from the distal segment. Subsequently the frequency of the slow waves from this segment approaches that of the proximal segment. The restoration of the slow-wave plateau at the beginning of the small intestine depends both on the amplitude and on the frequency of the stimulating impulses. On the background of antagonists of the cholinergic (atr. sulf. 200 microgram/kg) and of the adrenergic systems (propranolol 2 mg/kg and phentolamine 1 mg/kg), increasing the frequency of the slow waves of the segment which is distal to the section requires an increase in the amplitude of the stimulating impulses. The role of the intrinsic nervous system for the assimilation of the slow-wave rhythm from the distal segment by the proximal one is discussed.