Dantrolene-Induced Inhibition of Skeletal L-Type Ca²⁺ Current Requires RyR1 Expression

Figure 2

Dantrolene does not affect steady-state inactivation of the fast skeletal muscle Na⁺ current. Representative recordings of skeletal Na⁺ current elicited by 20 ms depolarizations to 0 mV immediately following 300 ms prepulses ranging from −110 mV to −10 mV are shown for untreated control myotubes (a) and myotubes exposed to 10 𝜇M Dantrolene (b). The voltage protocol is not drawn to scale. (c) Voltage-dependence of inactivation for control (⚫; 𝑛=11) and Dantrolene-treated (⚪; 𝑛=8) myotubes. Inactivation was fit by (4) (see Section 2) with the following respective parameters for control and Dantrolene treated groups: 𝑉_1/2inact=−44.3±1.6 and −41.2±1.1 mV; 𝑘=−8.4±0.9 and −7.7±0.3 mV. Inactivation curves are superimposed with activation curves shown in Figure 1 to illustrate window current.

(a)

(b)

(c)