FIGURE 3.
Force-pCa relation in low Mg (open circles) and high Mg (solid circles). Steady isometric force F0 is expressed relative to the isometric force at saturating pCa (F0,S); vertical bars are SE. F0,S: in low Mg, 80 ± 5 kPa; in high Mg, 75 ± 5 kPa. Data from five fibers. Low Mg (continuous line) and high Mg (dashed line) are calculated from the Hill equation F0/F0,S = 1/(1+10n(pCa-pK)), where n, the Hill coefficient that expresses the steepness of the relation, and pK, the pCa at which F0 = 0.5 F0,S, are the parameters fitted by using a nonlinear least-squares method (SigmaPlot, SPSS Science Software). The best fit parameters are listed in the table
| n | pK | |
|---|---|---|
| Low Mg | 2.17 ± 0.14 | 5.89 ± 0.01 |
| High Mg | 1.97 ± 0.20 | 5.35 ± 0.02 |