Transgenic expression of fast skeletal muscle troponin T in mouse cardiac muscle significantly increased the cooperativity of Ca2+ activation (Hill coefficient 2.0 vs 1.0, P<0.05).
Absolute Event Rate: 2% vs 1%
p-value: p=< 0.05
1 To investigate the functional significance of different troponin T (TnT) isoforms in the Ca2+ activation of muscle contraction, transgenic mice have been constructed with a chicken fast skeletal muscle TnT transgene driven by a cardiac α-myosin heavy chain gene promoter. 2 Cardiac muscle-specific expression of the fast skeletal muscle TnT has been obtained with significant myofibril incorporation. Expression of the endogenous cardiac muscle thin filament regulatory proteins, such as troponin I and tropomyosin, was not altered in the transgenic mouse heart, providing an authentic system for the functional characterization of TnT isoforms. 3 Cardiac muscle contractility was analysed for the force vs. Ca2+ relationship in skinned ventricular trabeculae of transgenic mice in comparison with wild-type litter-mates. The results showed unchanged pCa50 values (5.1 ± 0.04 and 5.1 ± 0.1, respectively) but significantly steeper slopes (the Hill coefficient was 2.0 ± 0.2 vs. 1.0 ± 0.2, P < 0.05). 4 The results demonstrate that the structural and functional variation of different TnT isoforms may contribute to the difference in responsiveness and overall cooperativity of the thin filament-based Ca2+ regulation between cardiac and skeletal muscles.
Huang et al. (Fri,) conducted a other in Cardiac muscle contraction. Transgenic expression of fast skeletal muscle TnT vs. Wild-type litter-mates was evaluated on Force vs. Ca2+ relationship (Hill coefficient) (p=< 0.05). Transgenic expression of fast skeletal muscle troponin T in mouse cardiac muscle significantly increased the cooperativity of Ca2+ activation (Hill coefficient 2.0 vs 1.0, P<0.05).