Influence of morphine on the reversal of haemorrhagic shock induced by cholinergic drugs.

In haemorrhage-shocked rats, the recovery of mean arterial pressure (MAP), pulse pressure (PP) and respiratory rate (RR), as well as the improvement of survival rate, induced by the i.v. administration of centrally acting cholinergic drugs (physostigmine, oxotremorine) are not affected by morphine at the dose of 2.5 mg/kg i.v., and only partially (MAP, PP, survival rate) or not at all (RR) prevented by a dose of morphine of 5 mg/kg i.v. These results indicate that the anti-shock effect of cholinergic drugs is largely independent of the opioid tone, this possibly being of practical relevance.