The effect of coherin on the basic electrical rhythm of the dog ileum in vivo

Coherin, a substance isolated from the bovine posterior pituitary gland exists as a complex which is dissociated to yield at least two distinct enteroactive polypeptides, coherin A and B, and a third having little or no activity, coherin C. The effects of intravenous injection of nondissociated coherin (coherin G-25), coherin A, coherin B, vasopressin, and normal saline solution on the BER of the ileal Biebl loop in fasting dogs were investigated. The BER patterns in preinjection and postinjection periods were compared for each substance. The effects on the BER of each substance were compared with that of saline. Monopolar recordings were made from six electrodes 5 mm apart inserted into the ileal musculature of the Biebl loops. Coherin A significantly altered the electroenterograms in two ways. It increased phase locking in the ileal BER of the fasting dog and increased the amount of caudad BER propagation.