Sequence of cardiorespiratory effects of soman altered by route of administration.

Dilute soman was administered to anesthetized guinea-pigs by slow infusion (30 micrograms/kg/10 min); intravenous (IV), subcutaneous (SC), intraperitoneal (IP), intratracheal (IT), and upper-airway (UAW) routes were used. Times to ventilatory failure were 8.8 +/- 1.3 min (IV), 10.5 +/- 1.2 min (I.T.), 17.3 +/- 2.8 min (IP), 34.8 +/- 5.1 min (UAW), and 36.0 +/- 4.4 min (SC) for the 5 routes of exposure. Atrioventricular (AV) block occurred before ventilatory failure with all routes of challenge except IT and IP; when it did occur, AV block typically began after one-half reduction in minute volume. The results reflect the effects of rate of absorption and noncritical-site binding of the organophosphorus compound when all routes are compared and suggest that the pathogenesis of intoxication in the anesthetized guinea-pig is different when soman is infused into regions heavily enervated by vagal afferents.