| Group . | pCa 6.2 . | pCa 6.1 . | pCa 6.0 . | pCa 5.9 . |
|---|---|---|---|---|
| WT | ||||
| 0.5 µM OM | 62.3 ± 8.7 (*, P = 0.006) | 19.4 ± 4.0 (*, P = 0.02) | 6.44 ± 3.1 | −3.7 ± 4.3 |
| 1.0 µM OM | 157.4 ± 15.1 (*, P = 0.002; #, P = 0.001) | 62.7 ± 3.2 (*, P = 0.0003; #, P = 0.003) | 25.6 ± 5.2 (*, P = 0.02; #, P = 0.02) | 14.4 ± 4.4 (*, P = 0.04; #, P = 0.02) |
| SA | ||||
| 0.5 µM OM | 16.7 ± 16.2 | 10.3 ± 8.6 | 0.8 ± 4.2 | −0.02 ± 3.3 |
| 1.0 µM OM | 51.3 ± 7.9 (*, P = 0.007; &, P = 0.0003) | 32.5 ± 8.7 (*, P = 0.03; &, P = 0.03) | 15.4 ± 2.5 (*, P = 0.01) | 11.1 ± 2.4 (*, P = 0.02) |
| Group . | pCa 6.2 . | pCa 6.1 . | pCa 6.0 . | pCa 5.9 . |
|---|---|---|---|---|
| WT | ||||
| 0.5 µM OM | 62.3 ± 8.7 (*, P = 0.006) | 19.4 ± 4.0 (*, P = 0.02) | 6.44 ± 3.1 | −3.7 ± 4.3 |
| 1.0 µM OM | 157.4 ± 15.1 (*, P = 0.002; #, P = 0.001) | 62.7 ± 3.2 (*, P = 0.0003; #, P = 0.003) | 25.6 ± 5.2 (*, P = 0.02; #, P = 0.02) | 14.4 ± 4.4 (*, P = 0.04; #, P = 0.02) |
| SA | ||||
| 0.5 µM OM | 16.7 ± 16.2 | 10.3 ± 8.6 | 0.8 ± 4.2 | −0.02 ± 3.3 |
| 1.0 µM OM | 51.3 ± 7.9 (*, P = 0.007; &, P = 0.0003) | 32.5 ± 8.7 (*, P = 0.03; &, P = 0.03) | 15.4 ± 2.5 (*, P = 0.01) | 11.1 ± 2.4 (*, P = 0.02) |
The impact of OM on force generation was measured by incubating WT and SA myocardial preparations with either 0.5 µM or 1.0 µM OM. Baseline forces generated by the myocardial preparations were first measured in Ca2+ solutions with a range of pCa values from 6.2 to 5.9. Forces were subsequently measured on the same preparations using the same range of pCa solutions following a 2-min incubation with either 0.5 µM or 1.0 µM OM. The net increase in force generation following OM incubation at each pCa was calculated and expressed as percent increase in force from the baseline as done previously (Mamidi et al., 2015, 2017b). Data from multiple preparations from each heart were averaged, and 12–15 myocardial preparations from four different hearts were used per group. Values are expressed as mean ± SEM. #, Significantly different compared to the 0.5 µM OM group. *, Significantly different comparing baseline forces to the forces generated following incubation with OM within each group. &, Significantly different compared to the corresponding WT group.