Effect of Endotoxin on the S-A Node in Situ in the Dog Heart 1

Summary

Concentrations of endotoxin equivalent to those producing shock when given intravenously did not affect the S-A pacemaker activity of the dog in situ. Larger amounts of endotoxin, 100 μg to 1 mg, directly induced a negative chronotropic response, which was not blocked by atropine treatment. Endotoxin did not influence the effect of vagal stimulation and responses to acetylcholine and norepinephrine injected into the sinus node artery.