Response of the mesenteric circulation to serotonin in normal and atherosclerotic monkeys: implications for the pathogenesis of non-occlusive intestinal ischaemia.

We tested the hypothesis that atherosclerosis potentiates vasoconstrictor responses in the mesenteric circulation to stimulation of serotonergic and alpha-adrenergic receptors. In normal monkeys, infusion of serotonin had little effect on blood flow to the stomach, duodenum, and colon. In contrast, in atherosclerotic monkeys, serotonin produced a modest decrease in blood flow to the stomach and duodenum, and virtually abolished blood flow to the colon. Vasoconstrictor responses to phenylephrine in the stomach and duodenum were not altered by atherosclerosis, but responses were potentiated in the colon of atherosclerotic monkeys. In summary, atherosclerosis greatly potentiates vasoconstrictor responses to serotonin in the mesenteric circulation, particularly in vessels to the colon. We speculate that release of serotonin during adherence and aggregation of platelets at atherosclerotic lesions, coupled with augmented vasoconstrictor responses to serotonin, may play a role in the pathogenesis of non-occlusive mesenteric ischaemia.