Fig. 1.

Weaker contraction of transgenic mouse cardiomyocytes coexpressing fast troponin T (TnT) and cardiac TnT. A: representative shortening and relaxation traces demonstrated lower shortening amplitude with longer duration of the transgenic (TG) vs. wild-type (WT) cardiomyocytes. Arrow indicates the electrical stimulation of contraction. B: quantitative analysis found significantly smaller shortening amplitude of the TG cardiomyocytes than the WT control (**P < 0.01). Treatment of 30 nM isoproterenol (ISO) increased the shortening amplitudes of both groups (++P < 0.01) and diminished the difference seen at baseline.