Figure 4-13 The figure on the left shows the current from an oocyte that expresses the predominant nicotinic acetylcholine receptor subtype (α4β2) found in the central nervous system. Isoflurane (320 µM) reduces the peak current obtained in response to 1 µM acetylcholine from 2.4 µA to 1.1 µA (46% of control). The graph on the right shows the dose-response curve of the inhibition of α4β2 receptor subtype current by isoflurane. Notice that some inhibition of receptor function occurs even at an isoflurane concentration of about 0.1 minimum alveolar concentration (MAC). (Adapted from Flood P, Ramirez-Latorre J, Role L: α4β2 Neuronal nicotinic acetylcholine receptors in the central nervous system are inhibited by isoflurane and propofol, but α7-type nicotinic acetylcholine receptors are unaffected. Anesthesiology 86:859, 1997.)