FURTHER STUDIES OF SYMPATHETIC ACTIONS OF ANAESTHETICS IN INTACT AND SPINAL ANIMALS

Sympathetic activity was recorded before and during administration of various anaesthetic drugs, in animals of various species ventilated mechanically and given chloralose. Intravenously injected sodium bicarbonate solutions raised the discharge level transiently. Thiopentone and pentobarbitone depressed the discharge, as did methoxyflurane and Ēthrane; hypotension with Ēthrane was not directly attributable to central sympathetic inhibition. The activity was increased markedly by diethyl ether and chloroform, to a lesser extent by trichloroethylene, and erratically by teflurane. An increase in sympathetic discharge usually occurred on the addition of nitrous oxide to those agents which lowered activity. Ether caused significant preganglionic sympathetic excitation in cats subsequent to cervical cord transection.