Parameters of cardiomyocyte sarcomere dynamics. A. Peak cardiomyocyte shortening was greater in HG compared to nonHG at 2 and 4 Hz, but not at 6 Hz. Exposure to 32 μM [Zn2+]ex reduced peak shortening in both groups and abolished differences in peak shortening between the groups. B. Time to peak shortening was not different between HG and nonHG and not affected by zinc exposure. C. Both with and without [Zn2+]ex, maximum velocity of relengthening was greater in HG compared to nonHG at 2 and 4 Hz, but not at 6 Hz. Maximum velocity of relengthening in the nonHG group was enhanced with pacing frequency, but not as much in the HG group. D. Time to 50% relengthening was enhanced by 32 μM [Zn2+]ex in the HG group only. E. Diastolic sarcomere length was shorter in HG compared to nonHG and shortened in both groups by increasing pacing frequency. F. The change in diastolic sarcomere length with pacing frequency was greatest in HG cardiomyocytes not exposed to [Zn2+]ex. Exposure to 32 μM [Zn2+]ex in the HG cardiomyocytes recovered a normal response of diastolic sarcomere length to pacing frequency. #P<0.1, *P<0.05, †P<0.01; n=8 in each group.