Hemodynamics of Endotoxin Shock in the Rat and the Effects of Phenoxybenzamine. ∗

Summary

We have investigated the hemo-dynamics of endotoxin shock in the rat and the influence of phenoxybenzamine. Within a few minutes after injecting endotoxin there was a marked rise in portal venous pressure and a fall in both arterial pressure and mesen-teric blood flow. Considerable recovery of these values toward control occurred within 30 minutes after administration of endotoxin, following which there was a gradual decline in measured parameters till death. Animals pretreated with phenoxybenzamine had lower portal and arterial pressures and mesenteric blood flow before injection of endotoxin. The magnitude and direction of the early vascular responses to endotoxin were the same as in rats not administered the adrenergic blocking agent; however, arterial pressure and mesenteric perfusion failed to recover from the early effects of endotoxin in rats receiving phenoxybenzamine. Furthermore, prior treatment with phenoxybenzamine conferred no protection against the lethality of endotoxin although it reduced the severity of the intestinal lesions.