EFFECT OF HALOTHANE, ENFLURANE AND ISOFLURANE ON CAROTID BODY CHEMORECEPTOR ACTIVITY IN THE RABBIT AND THE CAT

The response of the carotid body chemoreceptors to administrationof halothane, enflurane and isoflurane was tested in the rabbitand cat. In the steady-state all three volatile anaesthetics,in doses up to 1%, were mildly chemodepressant. The oxygen responsecurves were shifted down-wards, but hypoxic stimuli below 5.3kPa over-came this chemodepression. Two-point carbon dioxideresponse curves were also shifted downwards, but with no changein slope. Possible mechanisms involved in the chemoreceptorresponse to transient and steady-state anaesthetic administrationare discussed.