Figure 4. Detection and compensation of an internal potassium leak in RyR1AG/+ muscle.
Fluorescence imaging of PBFI at 340 nm in Ryr1+/+ (A) and Ryr1AG/+ (B) soleus muscle in 3 mM Ringer's solutions. (C) Ratiometric potassium imaging obtained at 340 and 380 nm wavelengths provided a ratio of fluorescence in Ryr1+/+ (black) and Ryr1AG/+ (grey) soleus muscle (normalized to Ryr1+/+). (D) Representation of the ratiometric imaging experimental paradigms used in Figure 4 showing bath applications of 3 mM KCl, 7 mM KCl, 0 mM KCl, and 3 mM KCl with 2 μM glibenclamide in Ringer's solutions. (E) Slope of intracellular K+ fluorescence intensities in experimental conditions. (F, H) Normalized intracellular K+ concentration in Ryr1+/+ (black) and Ryr1AG/+ (grey) soleus muscle in 3 mM KCL (F, H) compared to soleus from contralateral limb in 7 mM KCl Ringer's solutions (F) or 3 mM KCL plus 2 μM Glibenclamide (H) (muscle was bathed in solutions for 1.5 hr before imaging, n is the number of fibers examined from four mice). (G) Rate of change in PBFI fluorescence after acute bath application of 2 μM Glibenclamide. Scale bar = 20 μm.
Figure 4—figure supplement 1. Serum level measurements from Ryr1+/+ (black bars) and Ryr1AG/+ (grey bars) in 2- and 6-month old mice.
