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. 1997 Dec 1;17(23):9157–9164. doi: 10.1523/JNEUROSCI.17-23-09157.1997

Fig. 1.

Fig. 1.

Expression of iNOS message and enzymatic activity after cerebral ischemia in B6 mice. A, Expression of iNOS message after focal cerebral ischemia. iNOS mRNA was determined by RT-PCR. A strong iNOS signal is observed at 48 and 96 hr after ischemia (top panel). The bottom panelshows the time course of the ratio of the optical density of the iNOS band by the density of the band corresponding to porphobilinogen deaminase (PBD), a housekeeping gene used for normalization. Significant elevation is observed at 48 and 96 hr after ischemia (p < 0.05; ANOVA and Tukey’s test). No expression is observed at 24 hr or 7 d (p > 0.05). B, iNOS enzymatic activity after cerebral ischemia. iNOS activity was measured using the citrulline conversion assay of Bredt and Snyder modified for detection of calcium-independent arginine-to-citrulline conversion, i.e., iNOS activity (Ross and Iadecola, 1996). Virtually no iNOS activity was observed in sham-operated mice. Substantial iNOS activity developed in the ischemic region 96 hr after MCA occlusion. The 96 hr time point was chosen because at this time iNOS message is maximal. These findings suggest that cerebral ischemia leads to expression of iNOS message and enzymatic activity in the injured brain.