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 administration of halothane, enflurane and isoflurane was tested in the rabbit and cat. In the steady-state all three volatile anaesthetics, in doses up to 1%, were mildly chemodepressant. The oxygen response curves were shifted downwards, but hypoxic stimuli below 5.3 kPa overcame this chemodepression. Two-point carbon dioxide response curves were also shifted downwards, but with no change in slope. Possible mechanisms involved in the chemoreceptor response to transient and steady-state anaesthetic administration are discussed.