Route-specific cardiorespiratory and neuromuscular changes following organophosphorous poisoning in rats

Organophosphorous compounds cause a variety of physiological effects. The effect of various routes of administration of these compounds on the pathophysiology is still an open question. The present study addresses the effect of two organophosphorous compounds, namely diisopropyl fluorophosphate and methylisopropyl phosphonofluoridate, given by two different routes (i.v. and s.c.), on physiological parameters in anaesthetized and artificially ventilated rats. Both organophosphorous compounds produced a dose-dependent rise in blood pressure, bradycardia and twitch potentiation after i.v. administration. These effects are mediated by muscarinic as well as alpha-adrenoreceptors and are not affected by adrenalectomy. However, after s.c. administration, both organophosphorous compounds produced a dose-dependent transient hypotension and bradycardia, mediated by muscarinic receptors, without affecting other physiological parameters. The results indicate the route-specific effects of these compounds on the cholinergic-catecholaminergic interactions in rats.