Minimum Alveolar Concentrations (MAC) of Isoflurane with and without Nitrous Oxide in Patients of Various Ages

Stevens, Wendell C.; Dolan, William M.; Gibbons, Robert T.; White, Alan G.; Eger, Edmond I.; Miller, Ronald D.; Jong, Rudolph H. de; Elashoff, Robert M.

doi:10.1097/00000542-197502000-00014

Cited by 305 publications

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“…In our study, isoflurane at concentrations of 1 to 3% induced a rapid (within minutes of the exposure) and significant increase in EAAT3 expression in the plasma membrane. These isoflurane concentrations are clinically relevant because 1 minimum alveolar concentration that inhibits a response to surgical stimuli in 50% of human subjects is 1.15% (in rats, it is ϳ1.4%; rat C6 cells and rat hippocampal synaptosomes were used in the study) (Stevens et al, 1975;Orliaguet et al, 2001); isoflurane concentrations higher than 1 minimum alveolar concentration are frequently used in clinical practice. It is interesting that 2% isoflurane did not affect EAAT1 cell-surface expression in rat glial cells, suggesting that the effects of isoflurane on EAAT3 cell-surface expression are specific.…”

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confidence: 99%

Isoflurane Induces a Protein Kinase C α-Dependent Increase in Cell-Surface Protein Level and Activity of Glutamate Transporter Type 3

Huang¹,

Zuo²

2005

Mol Pharmacol

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Glutamate transporters regulate extracellular concentrations of glutamate, an excitatory neurotransmitter in the central nervous system. We have shown that the commonly used anesthetic isoflurane increased the activity of glutamate transporter type 3 (excitatory amino acid transporter 3, EAAT3) possibly via a protein kinase C (PKC)-dependent pathway. In this study, we showed that isoflurane induced a time-and concentrationdependent redistribution of EAAT3 to the cell membrane in C6 glioma cells. This redistribution was inhibited by staurosporine, a pan PKC inhibitor, or by 12-(2-cyanoethyl)-6,7,12,13-tetrahydro-13-methyl-5-oxo-5H-indolo(2,3-a)pyrrolo(3,4-c)-carbazole (Gö 6976) at a concentration that selectively inhibits conventional PKC isozymes (PKC␣, -␤, and -␥). This isoflurane-induced EAAT3 redistribution was also blocked when the expression of PKC␣ but not PKC␤ proteins was down-regulated by the respective antisense oligonucleotides. The isoflurane-induced increase of glutamate uptake by EAAT3 was abolished by the down-regulation of PKC␣ expression. Immunoprecipitation with an anti-EAAT3 antibody pulled down more PKC␣ in cells exposed to isoflurane than in control cells. Isoflurane also increased the phosphorylated EAAT3 and the redistribution of PKC␣ to the particulate fraction of cells. Consistent with the results in C6 cells, isoflurane also increased EAAT3 cell-surface expression and enhanced the association of PKC␣ with EAAT3 in rat hippocampal synaptosomes. Our results suggest that the isoflurane-induced increase in EAAT3 activity requires an increased amount of EAAT3 protein in the plasma membrane. These effects are PKC␣-dependent and may rely on the formation of an EAAT3-PKC␣ complex. Together, these results suggest an important mechanism for the regulation of glutamate transporter functions and expand our understanding of isoflurane pharmacology at cellular and molecular levels.Glutamate transporters (also called excitatory amino acid transporters, EAAT) are important in regulating extracellular concentrations of glutamate (Danbolt, 2001), a major excitatory neurotransmitter in the mammalian central nervous system (CNS). By transporting glutamate from extracellular to intracellular space under physiological conditions, EAATs prevent extracellular glutamate accumulation and regulate glutamate neurotransmission. Five EAATs have been identified: EAAT1 to EAAT5 (Danbolt, 2001). In rats, EAAT1 and EAAT2 are found in glial cells, and EAAT3 and EAAT4 are mainly expressed in neurons, whereas EAAT5 is located in neurons and glial cells of retina (Rothstein et al., 1994;Lehre et al., 1995;Arriza et al., 1997). The transporting functions of all five EAATs are sodium-dependent. They use the transmembrane gradient of Na ϩ , K ϩ , and H ϩ as a driving force to uptake glutamate (Billups et al., 1998;Danbolt, 2001).Studies on regional distribution of EAATs have shown that EAAT3 is widely distributed in forebrain, hippocampus, and cerebellum and that EAAT4 is largely restricted to the molecular cell layer ...

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confidence: 99%

Isoflurane Induces a Protein Kinase C α-Dependent Increase in Cell-Surface Protein Level and Activity of Glutamate Transporter Type 3

Huang¹,

Zuo²

2005

Mol Pharmacol

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“…A soft catheter was inserted about 2 cm into the nostril to monitor end-tidal carbon dioxide and end-tidal concentrations of isoflurane and sevoflurane (Anesthetic Gas Module M1026A; Agilent Technologies). [2][3][4] We assumed minimum alveolar anaesthetic concentration (MAC) values for isoflurane and sevoflurane of 1.15% 16 and 1.71%, 17 respectively. After breathing oxygen, general anesthesia was induced with 2 mg·kg -1 thiamylal iv for 15 sec, followed by 0.1 mg·kg -1 vecuronium iv.…”

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confidence: 99%

Les valeurs de l’index bispectral ne correspondent pas a la réponse hémodynamique à la suite de l’augmentation rapide de la concentration d’isoflurane

Nakayama

Hayashi

Ichinose

et al. 2001

Can J Anesth/J Can Anesth

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P Pu ur rp po os se e: : To investigate the changes in hemodynamic variables and bispectral index (BIS) in response to a rapid increase in isoflurane or sevoflurane concentration.M Me et th ho od d: : Thirty adult patients were anesthetized with either isoflurane (isoflurane group) or sevoflurane (sevoflurane group). Two minutes after induction of anesthesia with thiamylal, the inspired concentrations of isoflurane and sevoflurane were rapidly increased from 0.5 minimum alveolar anaesthetic concentration (MAC) to 3 MAC and maintained for five minutes. Heart rate (HR), mean arterial pressure (MAP), and BIS were measured every minute.R Re es su ul lt ts s: : An increase in the anesthetic concentration caused increases in HR and MAP in the isoflurane group and a decrease in MAP in the sevoflurane group. Consequently, HR and MAP in the isoflurane group were significantly higher than those in the sevoflurane group. After inhalation of high concentrations, BIS significantly and progressively decreased in both groups.

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“…The agent at 0.5 MAC 50 reduces contractility by 17% and frequency of spontaneous contraction by 13% while leaving the developed tension of contraction unchanged [7]. Assuming a MAC 50 of 1.28% for isoflurane [8] the concentration of isoflurane used in IN 2 O is 0.2 MAC 50 and so any effect would be less than that described by Munson & Embro [7].…”

Section: Discussionmentioning

confidence: 94%

The use of 0.25% isoflurane premixed in 50% nitrous oxide and oxygen for pain relief in labour

et al. 1999

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SummaryThe addition of 0.25% isoflurane to 50% nitrous oxide in oxygen provides more effective pain relief in labour than 50% nitrous oxide alone. This study was carried out to determine whether self-administration by demand valve of 0.25% isoflurane in 50% nitrous oxide in oxygen premixed in cylinders at 13.7 MPa (IN 2 O) was practical and safe during labour. Two hundred and twentyone mothers used IN 2 O in labour after 50% nitrous oxide had become inadequate for pain relief. Data on IN 2 O use was recorded during labour and details of the course of labour and opioid usage were taken from the clinical notes. The duration of IN 2 O use was 0.1-12.35 h (median 2.3). Thirty-two mothers (14.5%) required an epidural and intolerance to IN 2 O was seen in a maximum of 17 cases (7.7%). One hundred and twenty-six cases were primiparous and 93 parous with 151 deliveries being spontaneous and 70 interventional, of which 12 were by Caesarean section. Maternal blood loss was 20-1500 ml (median 200 ml). Apgar scores at 1 and 5 min were unaffected by IN 2 O use although a positive correlation was found between the use of opioids and the number of neonates with a 1-min score below 8 and the number requiring resuscitation. Six neonates had an Apgar score below 8 at 5 min, but their condition was adequately explained by factors other than the sedative technique used. Self-administered IN 2 O was found to be a safe and practical technique for sedation in labour when 50% nitrous oxide alone had become inadequate. The addition of isoflurane 0.2% or 0.25% to Entonox (premixed nitrous oxide : oxygen, 50/50, v/v) has been shown to provide more relief of pain from the contractions of labour than Entonox alone [1,2]. Such studies, however, have necessitated administration of the agent by an anaesthetist present in the labour room. Accordingly, we have premixed isoflurane with Entonox as a 0.25% vapour to form a stable and homogenous gas mixture stored at 13.7 MPa (IN 2 O) [3]. This mixture can be self-administered by women in labour using the same equipment as is required for Entonox. As in the case of Entonox, the premixture of any self-administered analgesic or sedative inhalational agents increases safety when used under the supervision of a nurse or paramedic. If the standard precautions are taken regarding cylinder storage and layering of the gas mixture is prevented, the oxygen cannot run out ahead of the other constituents, unduly high concentrations of active agent cannot be given and no mixing valves are required [4]. The demonstration of an improved level of analgesia for IN 2 O in comparison with Entonox under the necessarily controlled environment of the trials to date [1, 2] does not show that the addition of isoflurane to Entonox would be either safe or practical in the management of pain during labour in day-to-day midwifery practice. We therefore describe here the clinical course of 221 cases of selfadministration of premixed IN 2 O in labour under the control of the attendant midwife without direct supervision by medica...

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Minimum Alveolar Concentrations (MAC) of Isoflurane with and without Nitrous Oxide in Patients of Various Ages

Cited by 305 publications

References 0 publications

Isoflurane Induces a Protein Kinase C α-Dependent Increase in Cell-Surface Protein Level and Activity of Glutamate Transporter Type 3

Isoflurane Induces a Protein Kinase C α-Dependent Increase in Cell-Surface Protein Level and Activity of Glutamate Transporter Type 3

Les valeurs de l’index bispectral ne correspondent pas a la réponse hémodynamique à la suite de l’augmentation rapide de la concentration d’isoflurane

The use of 0.25% isoflurane premixed in 50% nitrous oxide and oxygen for pain relief in labour

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