Nitrous oxide depresses somatocardiac sympathetic A- and C-reflexes in anesthetized rats.
Effect of nitrous oxide (N2O) on the somatosympathetic A- and C-reflexes was investigated using artificially ventilated rats anesthetized with alpha-chloralose and urethane. Somatocardiac sympathetic A- and C-reflexes were elicited in the inferior cardiac nerve by electrical stimulation of A and C afferent fibers of the tibial nerve, respectively. Both reflexes were depressed by inhalation of N2O for 20 min. The depression was greater in the C-reflex than in the A-reflex. The depressive effects of N2O on both reflexes were unchanged after pretreatment with intravenous naloxone (0.2 or 2.0 mg/kg) or by prolongation of the inhalation of N2O for 2 h. These results suggest that the opioid receptor is not involved and that acute tolerance is not developed in the depressive action of N2O on the somatosympathetic A- and C-reflexes.
Adachi
T
T
Department of Anesthesia, Kyoto University Hospital, Japan. adachi@kuhp.kyoto-u.ac.jp
Miyazaki
Y
Y
Kurata
J
J
Utsumi
J
J
Shinomura
T
T
Nakao
S
S
Murakawa
M
M
Shichino
T
T
Mori
K
K
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D018686:Anesthetics, Intravenous / Q000494:pharmacology; D000818:Animals; D002698:Chloralose / Q000494:pharmacology; D004361:Drug Tolerance / Q000502:physiology; D004594:Electrophysiology; D006321:Heart / Q000294:innervation / Q000502:physiology; D008297:Male; D009609:Nitrous Oxide / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects*; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000502:physiology* / Q000601:surgery; D013979:Tibial Nerve / Q000187:drug effects / Q000502:physiology; D014520:Urethane / Q000494:pharmacology
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D002698:Chloralose; D014520:Urethane; D009609:Nitrous Oxide