1. Primary cultured myotubes were derived from satellite cells of the diaphragm obtained from both normal mice (RyR3+/+) and mice with a targeted mutation eliminating expression of the type 3 isoform of the ryanodine receptor (RyR3-/-). Using the whole-cell patch clamp technique, L-type Ca2+ currents were measured during step depolarizations. Simultaneously, intracellular Ca2+ transients were recorded with the fluorescent indicator dye fura-2. 2. After correction for non-instantaneous binding of Ca2+ to the indicator dye and taking into account the dynamics of Ca2+ binding to intracellular constituents, an estimate of the time course of the Ca2+ release rate from the sarcoplasmic reticulum (SR) was obtained. 3. The calculated SR Ca2+ release flux exhibited a marked peak within less than 12 ms after the onset of the voltage-clamp depolarization and fell rapidly thereafter to a five times lower, almost steady level. It declined rapidly after termination of the depolarization. 4. Signals in normal and RyR3-deficient myotubes showed no significant difference in the activation of Ca2+ conductance and in amplitude, time course and voltage dependence of the Ca2+ efflux from the SR. 5. In conclusion, the characteristics of voltage-controlled Ca2+ release reported here are similar to those of mature mammalian muscle fibres. In contrast to differences observed in the contractile properties of RyR3-deficient muscle fibres, a contribution of RyR3 to excitation-contraction coupling could not be detected in myotubes.

Dietze, B., Bertocchini, F., Barone, V., Struk, A., Sorrentino, V., & Melzer, W. (1998). Voltage-controlled Ca2+ release in normal and ryanodine receptor type 3 (RyR3)-deficient mouse myotubes. THE JOURNAL OF PHYSIOLOGY, 513(1), 3-9 [10.1111/j.1469-7793.1998.003by.x].

Voltage-controlled Ca2+ release in normal and ryanodine receptor type 3 (RyR3)-deficient mouse myotubes

Barone, V.;Sorrentino, V.;
1998

Abstract

1. Primary cultured myotubes were derived from satellite cells of the diaphragm obtained from both normal mice (RyR3+/+) and mice with a targeted mutation eliminating expression of the type 3 isoform of the ryanodine receptor (RyR3-/-). Using the whole-cell patch clamp technique, L-type Ca2+ currents were measured during step depolarizations. Simultaneously, intracellular Ca2+ transients were recorded with the fluorescent indicator dye fura-2. 2. After correction for non-instantaneous binding of Ca2+ to the indicator dye and taking into account the dynamics of Ca2+ binding to intracellular constituents, an estimate of the time course of the Ca2+ release rate from the sarcoplasmic reticulum (SR) was obtained. 3. The calculated SR Ca2+ release flux exhibited a marked peak within less than 12 ms after the onset of the voltage-clamp depolarization and fell rapidly thereafter to a five times lower, almost steady level. It declined rapidly after termination of the depolarization. 4. Signals in normal and RyR3-deficient myotubes showed no significant difference in the activation of Ca2+ conductance and in amplitude, time course and voltage dependence of the Ca2+ efflux from the SR. 5. In conclusion, the characteristics of voltage-controlled Ca2+ release reported here are similar to those of mature mammalian muscle fibres. In contrast to differences observed in the contractile properties of RyR3-deficient muscle fibres, a contribution of RyR3 to excitation-contraction coupling could not be detected in myotubes.
Dietze, B., Bertocchini, F., Barone, V., Struk, A., Sorrentino, V., & Melzer, W. (1998). Voltage-controlled Ca2+ release in normal and ryanodine receptor type 3 (RyR3)-deficient mouse myotubes. THE JOURNAL OF PHYSIOLOGY, 513(1), 3-9 [10.1111/j.1469-7793.1998.003by.x].
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11365/20816
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