Figure 2.

Effect of SHS on APD alternans. (A–C) Average APD spectral alternans magnitude is plotted against the pacing cycle length (PCL) following (A) 4- ($n=4/\text{group}$), (B) 8- ($n=4/\text{group}$), and (C) 12- (FA $n=4$; SHS $n=4–5$) wk of exposure to FA (circles) or SHS (squares). Data was analyzed with two-way analysis of variance (ANOVA) with Tukey’s posthoc test. Data is shown as $\text{mean}\pm \text{standard \hspace{0.17em} error \hspace{0.17em} of \hspace{0.17em} the \hspace{0.17em} mean \hspace{0.17em}}\left(\text{SEM}\right)$. (D) Representative APD alternans magnitude maps following 12 wk of exposure at decreasing PCLs. (E) Representative optical $V_{\mathrm{m}}$ traces from the location indicated in square cutout red box in (D). Note: APD, action potential duration; FA, filtered air; L, longer APD; PCL, pacing cycle length; S, shorter APD; SHS, secondhand smoke.