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. Author manuscript; available in PMC: 2020 Feb 15.
Published in final edited form as: Arch Biochem Biophys. 2018 Dec 18;662:213–218. doi: 10.1016/j.abb.2018.12.021

Figure 1. Representative stretch activation response in wild-type (WT) mouse myocardium.

Figure 1.

The important phases of the force transient and various stretch activation parameters are highlighted. In an isometrically contracting mouse myocardial preparation, a sudden 2% stretch in muscle length (Phase 1) induces an abrupt spike in force (P1) due to strained elastic elements within the strongly bound XBs. Force then rapidly decays (Phase 2), with a rate constant krel and magnitude P2, due to the detachment of the strained XBs into a non-force bearing state. Next, there is a delayed force redevelopment (Phase 3), with a rate constant kdf, as XBs reenter force-bearing states via stretch-induced cooperative recruitment to reach a higher steady state force level (P3). Pdf denotes the magnitude of XB recruitment and is the difference between P3 and P2. For a detailed description of various phases, refer to [22, 23].