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. Author manuscript; available in PMC: 2018 Nov 1.
Published in final edited form as: Prog Biophys Mol Biol. 2017 Jun 22;130(Pt B):281–287. doi: 10.1016/j.pbiomolbio.2017.06.009

Figure 2. Typical Slow Force Response recordings in wild-type (WT) and giant titin homozygous mutant (HM) isolated rat cardiac trabeculae.

Figure 2

Sarcomere stretch (ΔSL=0.2 μm) from baseline diastolic SL (red traces) led to an immediate increase in twitch force (green traces); maintaining diastolic SL at the longer length for a further 5.5 minutes induced a further increase in twitch force (blue traces), reflecting the Slow Force Response (SFR) phenomenon (see also Figure 3 and Table 2). The SFR was smaller in HM compared to WT muscles; twitch kinetics were, overall, faster in HM compared to WT muscles, consistent with the average twitch kinetics recorded at saturating bath [Ca2+]o (2 mM; Table 1). [Ca2+]o=0.4 mM; stimulus frequency=1 Hz; temperature=25 °C.