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. 2004 Aug;87(2):929–942. doi: 10.1529/biophysj.104.043810

FIGURE 3.

FIGURE 3

Ca2+ transients expressed by β1a-β2a chimeras in β1 KO myotubes. Open symbols correspond to peak ΔF/F obtained with a 200-ms depolarization and solid symbols were obtained with a 50-ms depolarization. Except for β1a(D1–D4)/β2aD5, the lines correspond to a Boltzmann fit of the mean (peak ΔF/F) for the population of cells. For β1a(D1–D4)/β2aD5, the lines are an interpolation of the mean at each potential. All fluorescence versus voltage curves were fit with Eq. 1, except those obtained with the 200 ms depolarization in the bottom row, which were fit with Eq. 2. Curves were fit with the following parameters (ΔF/Fmax in ΔF/F units, V1/2 in mV, and k in mV, respectively). For β2a(D1–D3)/β1a(D4, D5): 2.5, −5.5, 8.4 (50 ms), and 2.9, −7.1, 8.0 (200 ms); for β2a(D1–D4)/β1aD5: 2.3, 2.8, 5.8 (50 ms) and 2.5, −1.5, 5.5 (200 ms); and for β1a(D1–D3)/β2a(D4, D5): 0.2, −16.3, 13.4 (50 ms) and 0.9, 11.1, 1.9 (200 ms).