Figure 3.

Effects of parvalbumin expression on diseased cardiac myocyte relaxation rates. (A) Sarcomere relaxation records from representative control and parvalbumin-expressing myocytes isolated from euthyroid and hypothyroid rats. (B) Relaxation parameters from control and parvalbumin-expressing myocytes from hypothyroid rats (open bars) at 37°C. * indicates significantly different from hypothyroid control and lacZ. Parameters from control euthyroid rat myocytes (filled bars) included for comparison. Differences in sarcomere shortening parameters for hypothyroid myocytes were qualitatively similar to euthyroid rat myocyte parameters (Table 1) with t_peak = 68.1 ± 2.9, 53.9 ± 3.2*, 78.7 ± 3.4*, and +dl/dt_max = 7.36 ± 0.43, 8.98 ± 0.44, 6.58 ± 0.49 (mean ± SEM) for control (n = 26), parvalbumin- (n = 20), and lacZ- (n = 32) expressing hypothyroid myocytes. * indicates significantly different from hypothyroid control (P < 0.05).