The sensitivity of the Bezold-Jarisch reflex is increased in rats with sinoaortic deafferentation.

The sensitivity of the Bezold-Jarisch reflex was evaluated by the cardiovascular changes in response to intravenous injection of increasing doses of serotonin (5-hydroxytryptamine) in conscious male Wistar (300-350 g) rats 1 and 15 days after sinoaortic deafferentation. The bradycardia and hypotension induced by serotonin (2, 4, 8, 16 and 32 micrograms, iv) were does dependent in sinoaortic deafferentated as well as in sham-operated rats, but the magnitude of the bradycardiac and depressor response to all doses of serotonin was significantly greater in both groups of sinoaortic deafferentated rats [1 (N = 8) and 15 days (N = 8)] than in sham-operated animals [1 (N = 8) and 15 days (N = 8)], indicating an increased sensitivity of the Bezold-Jarisch reflex. These data suggest that the increased sensitivity of the Bezold-Jarisch reflex may have some functional role in cardiovascular regulation after removal of aortic and carotid baroreceptors.