The hemodynamic effects of sympathetic stimulation combined with parasympathetic blockade in man

J R Stratton, M A Pfeifer, J B Halter
1987 Circulation  
To define the effects of circulating norepinephrine and epinephrine on cardiac function and to determine whether left ventricular function is influenced by parasympathetic mechanisms during catecholamine stimulation, hemodynamic changes were investigated in healthy young human subjects who were supine and awake during infusion of (1) intravenous norepinephrine alone (125 ng/kg/min) (n = 6), (2) norepinephrine (125 ng/kg/min) plus epinephrine (50 ng/kg/min) (n = 6), and (3) norepinephrine plus
more » ... repinephrine plus epinephrine plus parasympathetic blockade induced by atropine (2 mg intravenously) (n 5). Ejection fraction and changes in cardiac volumes were measured by radionuclide ventriculography. During the infusion of norepinephrine plus epinephrine, plasma norepinephrine increased from 358 ± 35 to 1782 ± 123 pg/ml (mean ± SE) and plasma epinephrine increased from 31 ± S to 355 ± 90 pg/ml (both p < .01 vs baseline). These increases in plasma catecholamines were associated with increases in the heart rate (58 ± 3 to 67 2 beats/min, p = NS), systolic blood pressure (113 + 3 to 140 + 6 mm Hg, p < .01), ejection fraction (0.64 + 0.02 to 0.72 0.02 ejection fraction units, p < .01), stroke volume ( + 41 5%, p < .01), and cardiac output ( + 54 8%, p < .01), and a decrease in systemic vascular resistance (-31 3%, p < .01). Administration of atropine during the concurrent infusion of catecholamines led to additional increases in heart rate (127 ± 5 beats/min), systolic pressure (179 ± 10 mm Hg), ejection fraction (0.83 ± 0.05), stroke volume (+58 + 5%), and cardiac output ( + 262 + 18%), and a decrease in systemic vascular resistance ( -63 + 1%) (all p < .05 compared with baseline and with norepinephrine plus epinephrine alone). These findings define in part the range of hemodynamic changes controlled by sympathetic and parasympathetic mechanisms in normal subjects. The augmentation of ejection fraction and stroke volume by the infusion of atropine supports the concept that parasympathetic inhibition of ventricular performance occurs in man. Circulation 75, No. 5, 922-929, 1987. : Exercise, dobutamine, and combined atropine, norepinephrine and epinephrine compared.
doi:10.1161/01.cir.75.5.922 pmid:3568309 fatcat:eg2hueyk6bdnvibprzlyp43scm