Effect of blockade of the reticuloendothelial system on the carbaryl toxicity in the rat.

The time dependence of the level of blood cholinesterase was determined in rats with the reticulo-endothelial system (RES) inhibited with colloidal carbon and in control rats after i.v. administration of 2 does of carbaryl: 0.75 mg and 1.50 mg/100 g body wt. Pretreatment with colloidal carbon had no effect on the blood cholinesterase activity when compared with the controls. Carbaryl rapidly inhibits cholinesterase; the time of "reactivation" of this enzyme increases with the administered dose. However, when the RES is inhibited with colloidal carbon, "reactivation" of cholinesterase is significantly slowed down, to a varying degree, depending on the dose of carbaryl. Our results bring to light a relationship between the inhibition of the RES and the toxicity of carbaryl, inhibition increasing the anticholinesterase effect of the insecticide.