Fig. 2
From: Impaired Ca2+ release contributes to muscle weakness in a rat model of critical illness myopathy
Ca2+ release from the sarcoplasmic reticulum is reduced and non-uniform in muscle fibers from ICU rats. Panels a-d show representative line scans of fluo-3 fluorescence from flexor digitorum brevis (FDB) fibers during three 70-Hz tetani at 2-s intervals. a Typical homogeneous free myoplasmic [Ca2+] ([Ca2+]i) transient during each of the three tetani seen in sham-operated (SHAM) rat fibers. b-d The [Ca2+]i transients observed in ICU rat fibers. b Ca2+ release is seen only at one edge of the fiber. c The [Ca2+]i transients do not occur in response to each tetanic stimulation and do not last throughout the whole period of electrical stimulation. d The [Ca2+]i transients occurred during each of the three tetani but were reduced compared to those in SHAM rat fibers. Fluorescence intensity (F) is expressed relative to the value at rest (F 0 ). Periods of electrical stimulation are indicated by the black bars underneath each trace. Calibration bar to the right of each line scan is 50 μm