Cardiovascular responses to noradrenaline in the rat before and after administration of various anaesthetics.

1. Cardiovascular responses to intravenously administered noradrenaline were monitored in the rat in the conscious state and again following anaesthesia. Injections and pressure recordings were made via permanently implanted venous and arterial catheters.2. The pressor response to noradrenaline was inhibited by diethyl ether, urethane and deep pentobarbitone anaesthesia. It was unchanged by ketamine and was potentiated by chloralose and light pentobarbitone anaesthesia.3. Reflex bradycardia was potentiated by chloralose, blocked by ketamine and reduced by pentobarbitone. It was either reduced or unchanged by ether or urethane.