DIVERGENT EFFECT OF SALINE AND GLUCOSE SOLUTIONS ON MYOELECTRIC AND MOTOR-ACTIVITY OF CANINE SMALL-BOWEL

Previous work has shown that stimulation of osmotic receptors in the duodenal mucosa is followed by an increase in small intestinal motility. This effect was consistently observed with saline solutions, while stimulation or inhibition is observed when glucose is the solute. To gain further insight into the mechanisms of these apparent contradictory effects, we have perfused the intestine with saline and glucose solutions while simultaneously recording small bowel electrical and motor activity. Also to elucidate the influence of the spontaneous fasting activity, infusions were done on two different phases of the migrating motor complex infusion of 10 ml of both NaCl and glucose (1250 and 2500 mOsm/kg) in Phase I of the migrating motor complex, elicited the appearance of spike potentials and contractions. When infused during Phase II, NaCl caused an increase in the frequency of the irregular motor activity characteristics of this phase, due to a greater coupling of electrical and motor events. Also a greater amplitude of contractions was seen. In contrast, glucose infusion in Phase II was associated with a decrease of both electrical events and contractions. We conclude that the effect of hyperosmolar solutions is influenced by the solute and the phase of the migrating motor complex in which they are infused.