Responses to pressor substances in conscious and anaesthetized cats

The blood pressure responses to intravenous injections of noradrenaline, tyramine and McN-A-343 have been determined in conscious cats and in cats under pentobarbitone sodium, alpha-chloralose, urethane or alpha-chloralose plus urethane anaesthesia. All four anaesthetic agents reduced the pressor responses, the reduction being most pronounced with urethane and least pronounced with alpha-chloralose. Pentobarbitone sodium exerted a greater inhibitory effect on the responses to McN-A-343 than on those to noradrenaline or tyramine.