The anesthetic excitement phase occurring during induction of anesthesia with volatile anesthetics is a well-known phenomenon in clinical practice. However, the physiological mechanisms underlying anesthetic-induced excitation are still unclear. Here we provide evidence from in vitro experiments performed on rat brain slices that the general anesthetic isoflurane at a concentration of about 0.1 mM can enhance neuronal network excitability in the hippocampus, while simultaneously reducing it in the neocortex. In contrast, isoflurane tissue concentrations above 0.3 mM expectedly caused a pronounced reduction in both brain regions. Neuronal network excitability was assessed by combining simultaneous multisite stimulation via a multielectrode array with recording intrinsic optical signals as a measure of neuronal population activity.
References
[1]
Guedel AE (1920) Third stage ether anesthesia: a sub-classification regarding the significance of the position and movement of the eyeball. Am. J. Surg Q Suppl Anesth Analg 34: 53–57.
[2]
Fisher DM, Robinson S, Brett CM, Perin G, Gregory GA (1985) Comparison of enflurane, halothane, and isoflurane for diagnostic and therapeutic procedures in children with malignancies. Anesthesiology 63: 647–650.
[3]
Wren WS, McShane AJ, McCarthy JG, Lamont BJ, Casey WF, et al. (1985) Isoflurane in paediatric anaesthesia. Induction and recovery from anaesthesia. Anaesthesia 40: 315–323.
[4]
Sloan MH, Conard PF, Karsunky PK, Gross JB (1996) Sevoflurane versus isoflurane: induction and recovery characteristics with single-breath inhaled inductions of anesthesia. Anesth Analg 82: 528–532.
[5]
Hall JE, Oldham TA, Stewart JI, Harmer M (1997) Comparison between halothane and sevoflurane for adult vital capacity induction. Br J Anaesth 79: 285–288.
[6]
Martin JT, Faulconer A, Bickford RG (1959) Electroencephalography in anesthesiology. Anesthesiology 20: 359–376.
[7]
Ma JY, Shen BX, Stewart LS, Herrick IA, Leung LS (2002) The septohippocampal system participates in general anesthesia. J Neurosci 22 RC200: 1–6.
[8]
Antkowiak B (2002) In vitro networks: cortical mechanisms of anaesthetic action. Br J Anaesth 89: 102–111.
[9]
Dodt HU, Zieglg？nsberger W (1994) Infrared videomicroscopy: a new look at neural structure and function. Trends Neurosci 17: 453–458.
[10]
MacVicar BA, Hochman D (1991) Imaging of Synaptically Evoked Intrinsic Optical Signals in Hippocampal Slices. J Neurosci 11: 1458–1469.
[11]
Holthoff K, Dodt HU, Witte OW (1994) Changes in intrinsic optical signal of rat neocortical slices following afferent stimulation. Neurosci Lett 180: 227–230.
[12]
Zschokke S (1995) Klinische Elektroenzephalographie. Berlin: Springer.
[13]
Eder M, Becker K, Rammes G, Schierloh A, Azad SC, et al. (2003) Distribution and Properties of Functional Postsynaptic Kainate Receptors on Neocortical Layer V Pyramidal Neurons. J Neurosci 23: 6660–6670.
[14]
Campagna JA, Miller KW, Forman SA (2003) Mechanisms of actions of inhaled anesthetics. N Engl J Med 348: 2110–2124.
[15]
Dodt HU, D’Arcangelo G, Pestel E, Zieglg？nsberger W (1996) The spread of excitation in neocortical columns visualized with infrared-darkfield videomicroscopy. Neuroreport 7: 1553–1558.
[16]
Peixoto NLV, de Lima FVM, Hanke W (2001) Correlation of the electrical and intrinsic optical signals in the chicken spreading depression phenomenon. Neruosci Lett 299: 89–92.
[17]
Cerne R, Haglund MM (2002) Electrophysiological correlates to the intrinsic optical signal in the rat neocortical slice. Neruosci Lett 317: 147–150.
[18]
Maciver MB, Roth SH (1988) Inhalation Anesthetics Exhibit Pathway-Specific and Differential Actions on Hippocampal Synaptic Responses Invitro. Br J Anaesth 60: 680–691.
[19]
Simon W, Hapfelmeier G, Kochs E, Zieglgaensberger W, Rammes G (2001) Isoflurane blocks synaptic plasticity in the mouse hippocampus. Anesthesiology 94: 1058–1065.
[20]
Nishikawa K, MacIver MB (2001) Agent-selective effects of volatile anesthetics on GABA(A) receptor-mediated synaptic inhibition in hippocampal interneurons. Anesthesiology 94: 340–347.
[21]
Ranft A, Kurz J, Deuringer M, Haseneder R, Dodt HU, et al. (2004) Isoflurane modulates glutamatergic and GABAergic neurotransmission in the amygdala. Eur. J. Neurosci. 20: 1276–1280.
[22]
Perouansky M, Baranov D, Salman M, Yaari Y (1995) Effects of Halothane on Glutamate Receptor-Mediated Excitatory Postsynaptic Currents - A Patch-Clamp Study in Adult-Mouse Hippocampal Slices. Anesthesiology 83: 109–119.
[23]
Nishikawa K, Maciver MB (2000) Membrane and synaptic actions of halothane on rat hippocampal pyramidal neurons and inhibitory interneurons. J Neurosci 20: 5915–5923.
[24]
Franks NP, Lieb WR (1994) Molecular and Cellular Mechanisms of General-Anesthesia. Nature 367: 607–614.
[25]
Wakasugi M, Hirota K, Roth SH, Ito Y (1999) The effects of general anesthetics on excitatory and inhibitory synaptic transmission in area CA1 of the rat hippocampus in vitro. Anesthesia and Analgesia 88: 676–680.
[26]
Becker K, Eder M, Zieglg？nsberger W, Dodt HU (2005) Win 55,212–2 decreases the spatial spread of neocortical excitation in vitro. Neuroreport 16: 993–996.
