Effects of Nitrous Oxide on the Epileptogenic Property of Enflurane in Cats

Stevens, J.E.; Oshima, Eiji; Mori, Kenjiro

doi:10.1093/bja/55.2.145

Cited by 51 publications

(14 citation statements)

References 18 publications

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“…The synaptic interactions we found may contribute to the in vivo changes. There have been few studies of the synaptic effects of nitrous oxide, despite its wide use, but the transient potentiation of GABA responses which we found are interesting, as transient effects of this anaesthetic have been found on cortical evoked responses (Angel & Gratton, 1982) and on convulsant activity (Stevens, Oshima & Mori, 1983).…”

Section: Temperature Studiesmentioning

confidence: 61%

The effects of anaesthetics and high pressure on the responses of the rat superior cervical ganglion in vitro.

Little¹,

Thomas²

1986

The Journal of Physiology

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SUMMARY1. The effects of helium pressure and of general anaesthetics were studied on the responses of the isolated superior cervical ganglion of the rat, to determine how far these reflected the pressure reversal of anaesthesia seen in vivo. The method of Brown & Marsh (1974) for extracellular recording of surface potentials was adapted for use in a high-pressure chamber.2. Helium alone, at 130 atm, did not alter the responses of the ganglion to y-aminobutyric acid (GABA) but significantly depressed the depolarizing and hyperpolarizing components of the nicotinic responses, and the muscarinic responses.3. The potentiation of the responses to GABA caused by pentobarbitone was not altered by the application of helium, at 130 atm. This pressure also decreased further the nicotinic responses which were depressed by pentobarbitone.4. Nitrogen, at 34 atm (the anaesthetic ED50 in vivo) and at 68 atm, significantly decreased the nicotinic responses of the ganglia, and the addition of helium to a total of 130 atm further increased this depression. At pressures of 3-3-68 atm, nitrogen caused small decreases in the responses to GABA.5. Nitrous oxide at 1-5 atm (the ED50 for loss of righting reflex in mice) and at 3 atm, significantly depressed the responses to GABA and to the nicotinic agonist, but did not alter the responses to methylfurmethide. The effects of nitrous oxide were unaltered when helium was added to a total of 130 atm, although this pressure of helium added alone significantly depressed the cholinergic responses. A mixture of 50 % nitrous oxide and 50% oxygen, when added to the pressure chamber, at normal atmospheric pressure, caused transient increases in the responses to GABA.6. The effects of temperature on GABA responses and on nicotinic responses were very different from those of pressure. Preliminary evidence suggested that raising the temperature may decrease the extent of potentiation of GABA responses by pentobarbitone.7. The results are discussed in relation to the pressure reversal of anaesthesia in vivo. It was concluded that there was no evidence that the basis of this interaction lay in the potentiation of GABA responses by general anaesthetics, or the depression of cholinergic responses, although the changes seen were not in all cases simply additive. It was considered that effects ofgeneral anaesthetics such as the potentiation of GABA may contribute to the effects used to measure general anaesthesia in vivo, 13-2 H. J. LITTLE AND D. L. THOMAS such as loss of righting reflex, but may not be related to the non-specific actions which cause anaesthesia.

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Section: Temperature Studiesmentioning

confidence: 61%

The effects of anaesthetics and high pressure on the responses of the rat superior cervical ganglion in vitro.

Little¹,

Thomas²

1986

The Journal of Physiology

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“…During prolonged anaesthesia a state of tolerance develops and sudden cessation of nitrous-oxide induces hyperexcitability. 13 The duration of this case was half an hour so that nitrous-oxide withdrawal-induced hyperexcitability is unlikely.…”

Section: Discussionmentioning

confidence: 90%

Convulsions after enflurane in a schizophrenic patient receiving neuroleptics

Vohra

1994

Can J Anaesth

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“…Data values are expressed as means ± SEM (n = 5 and 6, for N 2 O and control groups, respectively). *P < 0.05 vs control values electroencephalography [9], anticonvulsive actions [10], activation of the dopaminergic system [11], and the enhancement of acetylcholine release [12]. The maximum effects of N 2 O in these studies were observed during the fi rst 30 min, subsiding gradually within 2 h, and then reaching a steady state.…”

Section: Introductionmentioning

confidence: 81%

Nitrous oxide increases serotonin release in the rat spinal cord

2007

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The mechanism of the antinociceptive action of nitrous oxide (N(2)O) is not fully understood. It was reported that N(2)O induces opioid peptide release in the rat midbrain, which can activate the descending inhibitory system in the spinal cord. Although effects of N(2)O on the noradrenergic descending inhibitory system have been established, effects of N(2)O on the serotonergic descending inhibitory system have not been extensively investigated. We measured the extracellular level of serotonin by using in vivo microdialysis in the dorsal horn of the spinal cord in rats. The serotonin release increased to 213.01 +/- 24.87% (mean +/- SEM) of the baseline level from 20 to 40 min after applying N(2)O, which was followed by a gradual decrease. It is suggested that the serotonergic descending pathway is activated by N(2)O.

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Effects of Nitrous Oxide on the Epileptogenic Property of Enflurane in Cats

Cited by 51 publications

References 18 publications

The effects of anaesthetics and high pressure on the responses of the rat superior cervical ganglion in vitro.

The effects of anaesthetics and high pressure on the responses of the rat superior cervical ganglion in vitro.

Convulsions after enflurane in a schizophrenic patient receiving neuroleptics

Nitrous oxide increases serotonin release in the rat spinal cord

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