Isoflurane does not depress the hypoxic response of rabbit carotid body chemoreceptors.
Whether volatile anesthetics have an effect on the peripheral chemoreceptors is controversial, possibly because of differences in end-tidal CO(2) concentrations. We studied the effect of isoflurane on the hypoxic chemosensitivity of carotid body chemoreceptors at three different PaCO(2) levels before and during the administration of 1.0% isoflurane (0.5 minimum alveolar anesthetic concentration) in six normothermic New Zealand white rabbits anesthetized with thiopental. The response of the chemoreceptors was fitted to the equation: Frequency (Hz) = a + b x PaCO(2) + c x (1/PaO(2)) + Dx (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 changed 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 concentration does not depress the hypoxic response of rabbit carotid body chemoreceptors during either hypo-, normo-, or hypercapnia.


CONCLUSIONS
By measuring single-fiber chemoreceptor activity in anesthetized rabbits, we showed that isoflurane at 1.0% end-tidal concentration does not depress the hypoxic chemosensitivity of peripheral chemoreceptors during either hypo-, normo-, or hypercapnia in this species.
Department of Anesthesiology and Intensive Care, Karolinska Hospital and Institute, Stockholm, Sweden. henning.joensen@dadlnet.dk
H
H
Joensen
C L
CL
Sadler
J
J
Ponte
Y
Y
Yamamoto
S G
SG
Lindahl
L I
LI
Eriksson
D000200:Action Potentials; D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D000818:Animals; D002245:Carbon Dioxide / Q000097:blood; D002344:Carotid Body / Q000187:drug effects* / Q000502:physiology / Q000503:physiopathology; D003864:Depression, Chemical; D000860:Hypoxia / Q000503:physiopathology*; D007530:Isoflurane / Q000494:pharmacology*; D010100:Oxygen / Q000097:blood; D011817:Rabbits
D018685:Anesthetics, Inhalation; D002245:Carbon Dioxide; D007530:Isoflurane; D010100:Oxygen