Myocardial function in feline endotoxin shock: a correlation between myocardial contractility, electrophysiology, and ultrastructure.

The nature of the myocardial depression observed in patients with septic shock, and in animals late in shock induced by endotoxin, is still under examination. These studies, in cats and kittens administered an LD80 dose of E coli endotoxin, were designed to examine the relationship between changes in myocardial contractility, in cellular electrophysiology and in ultrastructural morphology. There was no difference between tension developed in vitro by cardiac muscle removed from cats five hours after endotoxin administration and from cats not administered endotoxin. There was also no difference in their responses to calcium chloride or to anoxia. The action potential characteristics of ventricular muscle isolated from endotoxin treated cats were also not different from control, and ultrastructural damage was minimal and not extensive. Endotoxin (100 microgram/ml) had no effect on cardiac muscle in vitro, even after a one-hour contact time. It is concluded that the integrity of the myocardium is maintained even late in shock and that endotoxin has no direct effects on the heart.