Atropine-resistant excitation of motility of the dog stomach and colon induced by stimulation of the extrinsic nerves and their centers.

The atropine-resistant contraction of the alimentary canal, first reported by CAMPBELL (1966) and subsequently confirmed by others, was examined in dog in vivo. The gastric and colonic motor excitations were examined by stimulating the extrinsic nerves, the medulla oblongata or the spinal cord and its roots. Prolonged stimulation of the vagus, medulla oblongata or splanchnic nerve, thoracic cord and its dorsal root produced excitation of the gastric motility even after intravenous injection of sufficient atropine, although the intensity and frequency of peristalsis were slightly reduced. Prolonged latent periods were characteristic of the atropine-resistant excitation in the stomach, the latency being 29.8--49.4 sec as compared to 2.3--14.5 sec in control (without atropine). On the other hand, the colonic excitation induced by the stimulation of the pelvic nerve, or sacral cord and its ventral root was not inhibited by atropine; no prolongation in latency and reduction of peristalsis was observed.