RESUMEN
The [3[H]] acetylcholine of high specific activity has used been used to measure cholinergic binding sites in rat brain in the presence of diisopropyl fluorophosphate [DFP] to prevent hydrolysis and atropine to block muscarinic cholinergic receptors. The highest specific binding obtained when the assay mixture was incubated at 4°C. Equilibrium was attained after 3 minutes at 37°C, 10 minutes at 25°C and 1 hour at 4°C, however, the equilibrium binding was the same at the three levels of temperatures. The inhibitory effect of coumachlor, coumatetralyl and warfarin against the nicotinic acetylcholine receptors was also investigated. Warfarin was most effective compound in inhibiting the binding of [3[H]] acetylcholine while coumatetralyl was the least one in this respect