Calcium homeostasis in isolated EOM fibers. (A) Confocal
images of WT (a and b) and
ryr3−/− (c and d) fibers;
a and c show the transmitted light channel, and b and d show Mag-Fluo4
fluorescence, excited at 488 nm and recorded at an emission between 500
and 550 nm. Scale bar, 30 µm. (B) Representative line
scan traces of MagFluo4 calcium transients in EOM fibers from WT (black)
and ryr3−/− (gray), recorded
at 7,921 lines per second. (C) Measurements of resting
Ca2+ expressed as ratio (340/380 nm) using the
fluorescent indicator fura-2. Each symbol represents the ratio obtained
from a single fiber. The horizontal black line shows the mean value.
Fibers were isolated from a total of three mice per group, and a total
of 49 fibers from WT and 40 fibers from
ryr3−/− were analyzed.
(D) Peak Ca2+ (ΔF/F) of the MagFluo4
fluorescence obtained by stimulating EOM fibers by electrical field
stimulation with a 0.5-ms bipolar pulse. All experiments were performed
at room temperature. Each symbol represents the value from a single
fiber. The horizontal black line shows the mean value. A total of 14
fibers from four WT mice and 21 fibers from nine
ryr3−/− mice were
analyzed. (E) Analysis of the kinetics of the
Ca2+ transients; TTHP, TTP, and HRT of the calcium
transients are plotted. White dots, WT; gray dots,
ryr3−/−. A total of 12
fibers from four WT mice and 19 fibers from nine
ryr3−/− mice were
analyzed. *, P < 0.05; ***, P <
0.001, Student’s t test.