Supersensitivity due to prolonged administration of ganglion-blocking compounds.

Repeated subcutaneous injections of ganglionic blocking agents in cats were found to cause a supersensitivity towards adrenaline in the submaxillary gland and the nictitating membrane. The supersensitivity resembled that produced by preganglionic denervation, namely section of the chorda tympani in the case of the gland and of the cervical sympathetic trunk in the case of the membrane. The blocking compounds used were chlorisondamine chloride and hexamethonium. With the former, the sensitization could be obtained in the normally innervated structures. When hexamethonium was used, however, the effect on the gland could be produced only if the synapse had been made particularly susceptible to the blocking action of this agent; this was achieved by cross-suture experiments.