Insulin and jejunal electrical activity in dogs and sheep.

The effect of insulin on jejunal myoelectric activity was studied in conscious dogs and sheep by injection of insulin and stimulation of insulin release. In dogs, the migrating myoelectric complex (MMC), characteristic of fasting, was replaced by a continuous pattern of activity after feeding, injection of insulin, or infusion of D-glucose, L-leucine, or L-arginine. The response to feeding was reduced in alloxan-diabetic dogs and completely abolished following additional vagotomy when only exogenous insulin induced the "fed" pattern. Vagotomy alone had only minor effects on the response to feeding. Sheep exhibit a continuous sequence of MMC, regardless of feeding, but infusion of insulin or volatile fatty acids produced activity similar to that seen after feeding in dogs. In alloxan-diabetic sheep the recurrence and intensity of the MMC were decreased, and the effect of volatile fatty acids was eliminated. Insulin injection restored the pattern to normal. Thus, insulin levels are of importance in the control of the jejunal motor profile and may mediate the postprandial disappearance of MMC in dogs.