Arginine vasopressin response to anaesthesia produced by halothane, enflurane and isoflurane

Some of the effects of inhalational anaesthetics may be mediated by beta-endorphins acting on opioid receptors. Stimulation of such receptors has been shown both to promote and to inhibit the release of arginine vasopressin (AVP). Ten rabbits were studied to determine the response of plasma AVP to a predetermined time/concentration "dose" of halothane, enflurane or isoflurane. Abolition of corneal reflex was used as a standard end-point. Plasma samples were obtained from awake animals and after exposure to the anaesthetics, the sequence being randomly assigned. No significant changes in plasma AVP concentrations were observed when predetermined time/concentration "doses" of the agents were administered to the rabbits. Anaesthesia produced by halothane, enflurane or isoflurane, therefore, is not necessarily accompanied by changes in plasma AVP.