Vagal nerve contribution to the calcitonin-induced changes in intrapyloric pressure in anesthetized rats

The effect of calcitonin on intrapyloric pressure was examined in urethane-anesthetized rats. The intrapyloric pressure was decreased dose dependently by intravenous (i.v.) administration of 0.002-20 U of calcitonin. The calcitonin-induced decreased response was abolished after the severance of bilateral vagal nerves at the cervical level. Ongoing efferent activity of vagal gastric nerve branches was decreased by i.v. administration of calcitonin. On the contrary i.v. administration of calcitonin increased intrapyloric pressure via vagal nerves in atropinized or gallaminized animals. The contribution of the cholinergic excitatory and the non-cholinergic inhibitory vagal nerve fibers to the calcitonin-induced responses of intrapyloric pressure is discussed.