Fig. 1. SFR and p38-MAPK inhibition. A: Original force record from a rat papillary muscle stretched from 92 to 98 % of Lmax showing the classical "two-phase" response. Individual traces corresponding to the points indicated in the upper panel with "a" (before stretch), "b" (immediately after stretch) and "c" (5 minutes after stretch) are shown. B: Same as A, but from a muscle pre-incubated with the p38-MAPK inhibitor, SB202190 ("St+SB"), where it can be appreciated a greater SFR. C: same as A, but from a muscle pre-incubated with the SB202190 inactive analogous, SB202474 ("St+IA"). D: Averaged results after 5 minutes of stretch under all experimental conditions, expressed as a percentage of the initial rapid phase. Inset: The original force record shown in panel "A" was used to identify the characteristic two phases increase in force following myocardial stretch, as well as the calculation used to express the SFR in percentage form: "1" indicates the initial rapid phase generated immediately after stretch and considered as 100 %; "2" highlights the SFR observed at 5 minutes of stretch. The final magnitude of the SFR was calculated as (2 * 100 %)/1. * indicates p < 0.05 vs. all other groups.