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Figure 5 | BMC Physiology

Figure 5

From: Modulation of L-type Ca2+ current but not activation of Ca2+ release by the gamma1 subunit of the dihydropyridine receptor of skeletal muscle

Figure 5

Voltage-dependence of Ca2+ transients in γ 1 knockout and normal myotubes. A) Confocal line-scan images of fluo-4 fluorescence in response to a 50 ms step to +90 mV from a holding potential of -40 mV. Hot colors represent high fluorescence (yellow>red). The pulse was delivered 100 ms after the start of the line-scan as indicated at the bottom of the figure. Images have a horizontal dimension of 2.05 seconds in all cases. The vertical dimension was 15, 28, and 24 microns for the control, γ1 het, and γ1 null cells, respectively. The two curves on top of the image show the time course of the fluorescence intensity at -10 mV and +90 mV. 1 ΔF/Fo unit corresponds to a doubling of the cell resting fluorescence. B) Voltage-dependence of the peak ΔF/Fo for 6 control, 4 γ1 het, and 6 γ1 null cells. The curves correspond to a Boltzmann fit of the population mean with the following parameters. ΔF/Fomax = 3.8, V1/2 = 10 mV, k = 9.4 mV for control cells. ΔF/Fomax = 3.6, V1/2 = 10.8 mV; k = 10.9 mV for γ1 het cells. ΔF/Fomax = 3.7, V1/2 = 4.5 mV; k = 10 mV for γ1 null cells.

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