FIG. 3.

Effect of recombinant Grp94 expression on myofiber carbonylation of unloaded soleus muscles. *Student's t-test p<0.02; **p<0.001. (A) Presence and distribution of myofiber carbonylation vary after unloading and pT94 transfection. Consecutive transverse cryosections of ambulatory (amb) or unloaded (U) soleus muscles were exposed to DNPH, as described in “Materials and Methods”, and labeled with anti-DNPH antibodies (upper row) or stained for fast My (lower row) in indirect immunoperoxidase. Large and small arrowheads indicate representative DNPH-positive myofibers of the fast and slow fiber populations, respectively. Similarly, cryosections from U solei transfected with either Grp94 cDNA (pT94) or empty vector (pT), were reacted for DNPH (upper row) or labeled with anti-GFP antibodies (lower row). Arrows indicate DNPH-positive transfected myofibers. Bar: 50 μm. (B) Hindlimb unloading increases the percentage of carbonylated myofibers. Bars and error bars correspond to mean and SE values of the percentage of DNPH positive fibers evaluated on the total myofiber amount of ambulatory (A) and U solei, and, separatedly, on their respective fast and slow fiber populations. Average n of fibers considered for each muscle: 350. n indicates the number of muscles evaluated in each group. (C) Transfection with pT94 decreases the percentage of DNPH-positive myofibers in unloaded solei. Bars and error bars correspond to mean and SE values of the percentage of DNPH-positive fibers observed among myofibers transfected with pT94 or with pT. Average n of transfected fibers evaluated in each muscle: 80. DNPH, 2,4-dinitrophenylhydrazine. To see this illustration in color, the reader is referred to the web version of this article at www.liebertpub.com/ars