Fig. 7.

TnC4-knockdown eliminated positive work and power, but TnC1-knockdown had no effect on work or power. a Representative IFM work loops oscillated at a length change of 0.75 % ML and 100 Hz, pCa 5.0. Arrows indicate direction of work loops. Counterclockwise work loops indicate net positive work generating fibers and clockwise indicates work absorption. Both control and TnC1-knockdown fibers produced counter-clockwise work loops indicating they produce work and power while TnC4-knockdown fibers were clockwise indicating net work and power absorption. b Representative IFM work loops oscillated at a length change of 1 % ML amplitude, 125 Hz, pCa 5.0. c Power output by active (pCa 5.0) IFM fibers plotted against small amplitude, 0.125 % ML, sinusoidal oscillation frequency. No differences in the amount of power at any frequency or the frequency at which maximal power output occurs (f_max) were observed between TnC1 knockdown and WT fibers. No power was produced by TnC4-knockdown fibers at any frequency. N = 10 for both lines. d Power-pCa curve for TnC1-knockdown and WT IFMs normalized to 1 at pCa 5.0. Mean ± S.E.M. N = 12 for WT and TnC1-knockdown, N = 6 for TnC4 knockdown. e The frequency at which maximum power was generated (f_max) was the same for TnC1-knockdown and WT IFMs at all calcium concentrations. Mean ± S.E.M. N = 10 for both lines