Figure 7-21 Histograms depict myocardial infarct size as a percentage of area at risk in dogs pretreated with vehicle (Control) or pertussis toxin (PTX) in the presence or absence of 1.0 minimum alveolar concentration of isoflurane (ISO) or nicorandil (NIC). *, Significantly (P < .05) different from the control; †, significantly (P < .05) different from PTX alone; ‡, significantly (P < .05) different from PTX plus ISO. (Adapted from Toller WG, Kersten JR, Gross ER, et al: Isoflurane preconditions myocardium against infarction via activation of inhibitory guanine (Gi) nucleotide binding proteins. Anesthesiology 92:1400–1407, 2000.)