Potentiation of vasoconstrictor responses to serotonin in the limb of atherosclerotic monkeys.

Vasoconstrictor responses to serotonin and norepinephrine were examined in: normal cynomolgus monkeys, atherosclerotic monkeys that were fed atherogenic diet for 3-5 years and hypercholesterolaemic but non-atherosclerotic monkeys that were fed atherogenic diet for 4-5 months. Serotonin decreased total hindlimb resistance in normal and hypercholesterolaemic monkeys, but increased total resistance in atherosclerotic monkeys. There was a greater than 10-fold increase in constrictor responses of large arteries to serotonin in atherosclerotic compared with normal and hypercholesterolaemic monkeys. In contrast, responses to norepinephrine were not increased in atherosclerotic monkeys. Thus, atherosclerosis greatly potentiates constrictor responses to serotonin in large arteries of the limb. This potentiation appears to be somewhat selective for serotonin, as it is not observed with norepinephrine.