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+10
n(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 |
below.