| First Author | Ursu D | Year | 2001 |
| Journal | J Physiol | Volume | 533 |
| Issue | Pt 2 | Pages | 367-77 |
| PubMed ID | 11389198 | Mgi Jnum | J:106312 |
| Mgi Id | MGI:3618025 | Doi | 10.1111/j.1469-7793.2001.0367a.x |
| Citation | Ursu D, et al. (2001) Excitation-contraction coupling in skeletal muscle of a mouse lacking the dihydropyridine receptor subunit gamma1. J Physiol 533(Pt 2):367-77 |
| abstractText | 1. In skeletal muscle, dihydropyridine (DHP) receptors control both Ca(2+) entry (L-type current) and internal Ca(2+) release in a voltage-dependent manner. Here we investigated the question of whether elimination of the skeletal muscle-specific DHP receptor subunit gamma1 affects excitation-contraction (E-C) coupling. We studied intracellular Ca(2+) release and force production in muscle preparations of a mouse deficient in the gamma1 subunit (gamma-/-). 2. The rate of internal Ca(2+) release at large depolarization (+20 mV) was determined in voltage-clamped primary-cultured myotubes derived from satellite cells of adult mice by analysing fura-2 fluorescence signals and estimating the concentration of free and bound Ca(2+). On average, gamma-/- cells showed an increase in release of about one-third of the control value and no alterations in the time course. 3. Voltage of half-maximal activation (V(1/2)) and voltage sensitivity (k) were not significantly different in gamma-/- myotubes, either for internal Ca(2+) release activation or for the simultaneously measured L-type Ca(2+) conductance. The same was true for maximal Ca(2+) inward current and conductance. 4. Contractions evoked by electrical stimuli were recorded in isolated extensor digitorum longus (EDL; fast, glycolytic) and soleus (slow, oxidative) muscles under normal conditions and during fatigue induced by repetitive tetanic stimulation. Neither time course nor amplitudes of twitches and tetani nor force-frequency relations showed significant alterations in the gamma1-deficient muscles. 5. In conclusion, the overall results show that the gamma1 subunit is not essential for voltage-controlled Ca(2+) release and force production. |
