Isoflurane does not depress the hypoxic response of rabbit carotid body chemoreceptors

Whether volatile anesthetics have an effect on the peripheral chemoreceptor s is controversial, possibly because of differences in end-tidal CO2 concen trations. We studied the effect of isoflurane on the hypoxic chemosensitivi ty of carotid body chemoreceptors at three different Paco(2) levels before and during the administration of 1.0% isoflurane (0.5 minimum alveolar anes thetic concentration) in six normothermic New Zealand white rabbits anesthe tized with thiopental. The response of the chemoreceptors was fitted to the equation: Frequency (Hz) = a + b x Paco(2) + c x (1/Pao(2)) + D x (1/Pao(2 ))(2). Mean values for the coefficients a, b, c and d for the control state were -4.5, 0.13, 771, and 6332, respectively. This relationship was not ch anged by addition of isoflurane at 1.0% end-tidal concentration (P = 0.40, analysis of variance). We conclude that isoflurane at 1.0% end-tidal concen tration does not depress the hypoxic response of rabbit carotid body chemor eceptors during either hypo-, normo-, or hypercapnia.