[Hemodynamic effects of the Bezold-Jarisch reflex in rabbit]

The Bezold-Jarisch reflex induced by intracoronary injection of nicotine (ICIN) of 5 micrograms/kg was studied in 40 anesthetized rabbits. Heart rate (HR), arterial blood pressure (ABP), left ventricular pressure (IVP), left ventricular dp/dt (LV dp/dt) and cardiac output (CO) were monitored and total peripheral resistance (TPR) was calculated. HR, ABP, LVP and LV dp/dt were decreased following ICIN. These inhibitory responses induced by ICIN were enhanced by sino-aortic denervation but abolished by bilateral vagotomy. Decreases in CO and TPR were also observed in response to ICIN. With the heart paced artificially to prevent bradycardia, the decreases in CO, TPR and ABP were still significant. Bilateral stellate ganglion section plus atropinization which abolished the decreases in HR and CO, did not significantly change the hypotensive response to ICIN. These data suggest that the hypotension evoked by Bezold-Jarisch reflex in rabbit is largely due to the decreases in TPR and partially caused by the decrease in CO.