[Effect of M-cholinomimetics on nociceptive stimulation in the spinal cord]

Two series of experiments were performed to study the effects of oxotremorine (5, 10 and 20 micrograms/kg), arecoline (0.25, 0.5 and 1.0 mg/kg), pilocarpine (5, 10 and 20 mg/kg) and aceclidine (0.25, 0.5 and 1.0 mg/kg) injected intravenously on nociceptive transmission in the spinal cord of spinal rats. It was established that the m-cholinomimetics inhibit in a dose-dependent manner the nociceptive reflex induced by intraarterial injection of bradykinin. When given in the same doses the drugs reduce the bradykinin-induced bioelectrical activity in the afferent tracts of the spinal cord. Atropine (1 mg/kg i. v.) abolishes the antinociceptive action of the cholinomimetics.