Effects of L-type Calcium Channel Blocker Diltiazem on Manganese Contrast Enhancement. A. Mid point contrast enhancement in younger mice with no pharmacological treatment (left column), showing significant higher levels of mid point contrast enhancement in mdx and Sgcd−/− vs WT mice (+P< 0.05 versus WT, as in Figure 2C). Diltiazem 5 mg produced significant reductions in contrast enhancement in mdx (N=7) and WT (N=6) versus no treatment, though not for the Sgcd−/− mice (N=6). Diltiazem 10 mg produced a significant reduction in contrast enhancement in the Sgcd−/− mice (N=9); (+P<0.05 versus WT; *P<0.05 and **P<0.01 versus untreated, within same strain). B. Effects of diltiazem on heart rates. Diltiazem (5 mg) significantly reduced heart rates in WT and in mdx mice, though not in Sgcd−/− mice, a similar effect as seen with manganese contrast enhancement. Higher doses of diltiazem (10 mg) significantly reduced heart rates in the Sgcd−/− mice. (*P<0.05 versus without diltiazem).