Effect of naloxone on blood pressure and survival in different shock models in rats.

The effect of naloxone on a number of experimental shock models, using the anaesthetized rat, was studied with special emphasis on mean arterial blood pressure (MABP) and chance of survival. Only a slight increase in MABP was noted in haemorrhagic shock models whereas survival was not affected. Naloxone was without effect in endotoxin shock (i.p. administration of endotoxin). In endotoxin shock (i.v. administration) naloxone increased MABP especially at a high dose of endotoxin. Although survival time was prolonged, the chance of permanent survival was not improved. Naloxone had practically no effect in anaphylactic shock and intestinal ischaemia shock. It is concluded that if naloxone has any effect it is relatively slight. However, this does not exclude the possibility that naloxone might still be considered as an adjunct to other forms of shock treatment at least in certain types of shock.