Myocardial catecholamines and stimulation of the stellate ganglion in hemorrhagic shock

¹ Department of Physiology, Stritch School of Medicine and Graduate School, Loyola University, Chicago, Illinois

Cardiac responses to electrical stimulation of the right or left stellate ganglion were recorded from 16 open-chest anesthetized dogs in hemorrhagic shock. Shock was induced by bleeding the animals to a mean blood pressure of 40 mm Hg. This level of pressure was maintained for 4 hr, during which time blood pressure, heart rate, force of myocardial contraction, and intraventricular pressures were recorded. Stimulation of the stellate ganglion for 15–40 sec every 30 min after hemorrhage showed a gradual decrease in these parameters to levels below control. The reinfusion of blood and the infusion of exogenous l-norepinephrine did not restore an increase in force of cardiac contraction to stellate stimulation. Myocardial epinephrine and norepinephrine levels in shock were found not to differ from those in 14 normal dog hearts. In contrast to almost complete myocardial refractoriness to stellate stimulation in hemorrhagic shock, stimulation of the vagus nerve elicited bradycardia and eventual cardiac arrest. The decrease observed in force of cardiac contraction to stimulation of the stellate ganglion in hemorrhagic shock may be due to depletion of norepinephrine stores in the heart.

Key Words: stellate ganglia stimulation • cardiac sympathetic nerves • myocardial norepinephrine and cpinephrine

Submitted on August 11, 1964