Salutary effects of prostacyclin in endotoxic shock.

Endotoxin shock was induced in anesthetized cats with E. coli endotoxin (5 mg/kg, i.v.) This produced a severe decline in mean arterial blood pressure and a marked decrease in superior mesenteric artery flow (SMAF) within 1 h. The plasma activity of cathepsin D, a lysosomal protease, increased 6-fold by 2 h. At 5 h, myocardial depressant factor (MDF), a toxic of 0.75 nmol.kg-1.min-1 dilated the splanchnic circulation and significantly increased SMAF. In addition, PGI2 almost completely prevented the accumulation of cathepsin D and MDF in the circulating blood of cats given endotoxin. These findings suggest that PGI2 exerts a variety of beneficial actions in endotoxin shock including vasodilation and stabilization of lysosomal membranes. In addition, PGI2 is known to prevent platelet aggregation and suppress thromboxane formation, two additional effects that may be of positive survival value in endotoxin shock.