Journal of anesthesia
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Journal of anesthesia · Oct 1993
Effects of enflurane on gill withdrawal behaviors and the ability of gill motor neurones to elicit gill Contractions in Aplysia.
We used the Aplysia gill withdrawal reflex model system in order to study how enflurane effected both gill withdrawal adaptive behaviors and the activity of single identified neurones which are involved with the mediation of the gill withdrawal response. We found that a continuous superfusion of enflurane (O. ⋯ Although in most cases the ability of the motor neurone to elicit a gill withdrawal contraction was decreased, that in one third of the cases was increased. Enflurane may exert its actions by effecting the activity of CNS control neurones which exert both facilitatory and suppressive control over the peripheral nervous system in the gill as well as by having direct effects on the motor neurones.
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Journal of anesthesia · Oct 1993
Effects of halothane and isoflurane anesthesia on sympathetic adrenal nerve responses to carbon dioxide challenge in rats.
We studied the influence of two volatile anesthetics, halothane and isoflurane, on the circulatory and sympathetic nerve responses to carbon dioxide (9% CO2) in rats. Systolic blood pressure was depressed throughout the CO2 challenge and after an initial reduction, a gradual increase was observed in heart rate. Sympathetic adrenal nerve action potentials (SANA) significantly increased in contrast to negative responses in the circulatory functions. ⋯ The maximum changes in SANA from the baseline values were 110% and 40% for the halothane and isoflurane groups, respectively. The sympathetic reflex response to hyperacapnia was retained at 1.5 MAC for both anesthetics, though isoflurane depressed these responses more markedly than halothane. Our results suggest that halothane is a more preferable anesthetic than isoflurane when viewed from the standpoint of preservation of sympathetic nerve response in such undesirable situations as severe hypercapnia occurring during anesthesia.
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Journal of anesthesia · Oct 1993
Naloxone and flumazenil fail to antagonize the isoflurane-induced suppression of dorsal horn neurons in cats.
Effects of naloxone and flumazenil on isoflurane activities were examined on dorsal horn neurons in cats. Isoflurane suppressed bradykinin-induced nociceptive responses in transected feline spinal cords. The bradykinin-induced neuronal firing rates were significantly suppressed by 60.0%, 35.3% and 32.2% at 10, 20 and 30 min after isoflurane administration, respectively. ⋯ The suppressive effects of isoflurane were not reversed by naloxone (0.2 mg.kg(-1), i.v.). Similarly, the benzodiazepine antagonist, flumazenil (0.2 mg.kg(-1), i.v.), did not affect the suppressive effects of isoflurane. Failure of naloxone and flumazenil to reverse the suppressive effects of isoflurane suggests that isoflurane interacts with neither opioid nor benzodiazepine receptors in producing its suppressive action on nociceptive responses in dorsal horn neurons of the feline spinal cord.