Fig. 1
The methods of “bump” and “difference curve” of Ca2+ transients. a Ca2+ transient traces obtained under low or high stretch of a muscle (e.g., 85% and 95% LMAX) and normalized to their peaks. Thin line shows raw Ca2+ transient trace, thick line shows its monotonic component. The difference between the lines (“bump”) is indicated by arrows. b The time-based “bump” traces obtained from the transients shown in panel a. Certain characteristics of the “bump” are used for the analysis, e.g., its amplitude, integral intensity (an area under the “bump” trace), time-to-peak. c The superposition of normalized Ca2+ transient traces obtained under gradual stretch of a muscle as indicated by a long arrow. The trace obtained under no or minimal stretch is assumed as referent curve and this curve is subtracted from any other curve in the set. d The superposition of time-based “difference curves” obtained from the transients shown in panel c. Like the “bump”, the “difference curve” has certain characteristics, e.g., amplitude or integral intensity. Note that the difference curve has at least two components which are deflected upward (“positive” component) and downward (“negative” component). The characteristics shown here in panel d are related to the “positive” component of the “difference curve.” Please see the text for a detailed description