Nonmucosal serotonin levels as well as mucosal and blood levels were correlated with motility of the anoxic canine small intestine. Motility of the small intestine in the second hour of anoxia increased significantly as compared with that of the first hour. Nonmucosal serotonin was accumulated during anoxia, while mucosal serotonin remained near control levels.
The 29% mean increase of the nonmucosal serotonin was hardly enough to account for the increase in motility during anoxia. The data suggest that other substances that act on smooth muscle act directly on the muscle fiber and may be released from the anoxic intestine.
Abe H, Appert H, Carballo J, Howard JM. Nonmucosal Serotonin in Motility of the Small BowelWhen Subjected to Acute Anoxic Trauma. Arch Surg. 1973;106(2):183-187. doi:10.1001/archsurg.1973.01350140041013