Interaction of nitrous oxide and propofol to reduce hypertensive response to stimulation.
OBJECTIVE
To evaluate the interaction between nitrous oxide and propofol for the suppression of hypertension following electrical stimulation of the mental nerve in the rabbit.


METHODS
Male Japan White rabbits were tracheostomized, cannulated and mechanically ventilated under isoflurane anesthesia. Square wave pulses (5 V, 0.5 msec, 50 Hz for 5 sec) were delivered to the left mental nerve. Animals received nitrous oxide 20, 40, 60 and 80% (Group 1); propofol 200, 400, 600 and 800 microg x kg(-1) min(-1) (Group 2); or combinations of nitrous oxide and propofol at 10 + 100, 20 + 200, 30 + 300 and 40 % + 400 microg x kg(-1) x min(-1) (Group 3). Systolic blood pressure was recorded from immediately before to maximal increase following nerve stimulation. Probit analysis was used to obtain ED(50) values for 50% suppression of blood pressure elevation. Isobolographic analysis was used to evaluate the interaction between nitrous oxide and propofol.


RESULTS
ED(50) values are 52.9% for nitrous oxide (Group 1), 464.1 microg x kg(-1) min(-1) for propofol (Group 2), 21.7 % + 217.1 microg x kg(-1) min(-1) for nitrous oxide and propofol combination (Group 3) and 24. 7 % + 247.1 microg x kg(-1) x min(-1) for the theoretically additive combination of nitrous oxide and propofol, respectively.


CONCLUSIONS
The interaction between nitrous oxide and propofol for the suppression of blood pressure elevation following electrical stimulation of the mental nerve is additive.
Ichinohe
T
T
Department of Dental Anesthesiology, Tokyo Dental College, Chiba, Japan. ichinohe@tdc.ac.jp
Aida
H
H
Kaneko
Y
Y
D018685:Anesthetics, Inhalation / Q000494:pharmacology*; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004558:Electric Stimulation; D008297:Male; D008340:Mandibular Nerve / Q000502:physiology; D009609:Nitrous Oxide / Q000494:pharmacology*; D015742:Propofol / Q000494:pharmacology*; D011817:Rabbits
D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D009609:Nitrous Oxide; D015742:Propofol