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Differential effects of halothane and sevoflurane on hypoxia-induced intracellular calcium transients of neonatal rat carotid body type I cells† J.J. Pandit, K.J. Buckler British Journal of Anaesthesia Volume 103, Issue 5, Pages (November 2009) DOI: /bja/aep223 Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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Fig 1 Representative trace of [Ca2+]i (nM) during hypoxic protocols for halothane. The panels are rat values of 0.18, 0.91, and 1.45 MAC. Within each panel, the traces are sequentially: control, with background anaesthetic, after washout of anaesthetic. The periods of hypoxia and of anaesthetic exposure are shown by the horizontal bars. British Journal of Anaesthesia , DOI: ( /bja/aep223) Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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Fig 2 Representative trace of [Ca2+]i (nM) during hypoxic protocols for sevoflurane. The panels are rat values of (a) 0.2, (b) 1, and (c) 2 MAC. Within each panel, the traces are sequentially: control, with background anaesthetic, after washout of anaesthetic. The periods of hypoxia and of anaesthetic exposure are shown by the horizontal bars. British Journal of Anaesthesia , DOI: ( /bja/aep223) Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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Fig 3 (a) Boxplots showing distribution of absolute [Ca2+]i (nM) for each of the six test conditions. Hypoxia generally produces a large increase in [Ca2+]i, the calcium transient, which is greatly attenuated by halothane (all concentrations shown) but less so by sevoflurane (all concentrations shown). (b) Boxplots of the Ca2+ transients for control condition and each of four concentrations of halothane and sevoflurane, indicating the dramatic effect of halothane vs more modest effects of sevoflurane. The middle line of each box represents the median value, the edges of the box the inter-quartile range, the error bars the 10th and 90th deciles, and outliers are shown by single points. British Journal of Anaesthesia , DOI: ( /bja/aep223) Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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Fig 4 Dose (i.e. concentration)–response relationships for the effect of anaesthetic on relative magnitude of Ca2+ transient. Halothane depresses Ca2+ response more than sevoflurane at each dose. Values are means and for clarity, error bars show ±sem. British Journal of Anaesthesia , DOI: ( /bja/aep223) Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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Fig 5 Representative trace of [Ca2+]i (nM) during the control Ca2+-free protocol. (a) Halothane 1.81 MAC. (b) Sevoflurane 2 MAC. Within each panel, the traces are sequentially: standard Tyrode (Ca2+-Tyrode), Ca2+-free Tyrode, and Ca2+-free Tyrode with background anaesthetic. The periods of hypoxia and of anaesthetic exposure are shown by the horizontal bars. British Journal of Anaesthesia , DOI: ( /bja/aep223) Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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Fig 6 Boxplots showing distribution of individual cell responses [Ca2+]i (nM) for each of the eight test conditions to assess the effect of Ca2+-free solution. Hypoxia again produced a large increase in [Ca2+]i in standard Tyrode (Ca2+-Tyrode indicated by horizontal bar), but this did not occur in Ca2+-free solution (Ca2+-free indicated by horizontal bar). Indeed the value of [Ca2+]i was similar in Ca2+-free solution regardless of the presence of hypoxia or anaesthetic. The middle line of each box represents the median value, the edges of the box the inter-quartile range, the error bars the 10th and 90th deciles, and outliers are shown by single points (n=24 for the Ca2+-Tyrode protocols; n=12 for each of the Ca2+-free boxes). British Journal of Anaesthesia , DOI: ( /bja/aep223) Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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Fig 7 Representative plots of Ca2+ transients for the two agents: (a) and (b) two cell groups for halothane; (c) and (d) two cell groups for sevoflurane. Cells are bathed in 100 mM [K+] for ∼30 s, corresponding to the rapid increase in [Ca2+]i in each plot. Within each panel, the representative traces are sequentially: (i) control, (ii) with background anaesthetic, and (iii) after anaesthetic washout. Both agents depress the response to high-K+, but halothane appears to depress responses somewhat more than does sevoflurane. (e) Mean effect (sem) of each agent on the magnitude of the increase in [Ca2+]i with 100 mM [K+]. Values for both agents differ from unity (P<0.001), and the value for halothane differs from that for sevoflurane (*P=0.004). British Journal of Anaesthesia , DOI: ( /bja/aep223) Copyright © 2009 British Journal of Anaesthesia Terms and Conditions
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