Contractile force levels developed in rat muscles of the three experimental conditions.

<p>Evaluation of muscle strength in response to single twitch (<b>A</b>) and tetanus (<b>B</b>) in CTRL, RUN-S and RUN-F. *p < 0.05; **p < 0.01.</p

Morphological features of MTJ in control and trained rats.

<p>TEM images of MTJs which reveal the different complexity between control (<b>A</b>) and trained groups (RUN-F, <b>B</b>). At high magnification (13500x), tenocytes, located strictly close to MTJ (mtj), display, in comparison to control (<b>C</b>), a growing presence of rough endoplasmic reticulum (►) in trained groups (RUN-F, <b>D</b>). Bars <b>A</b>,<b>B</b>,<b>C</b>,<b>D</b>: 0.5μm.</p

mRNA levels of PGC-1α, Vinculin, IGF-1Ea and TGF-β in muscle.

<p>Effects of exercise protocols on PGC-1α (A), Vinculin (B), IGF-1Ea (C) and TGF-β (D) mRNA expression in EDL muscle, assessed by real-time PCR. Gene expression is represented as fold-change compared to untrained rats. Data are representative of three independent experiments. *p < 0.05.</p

mRNA levels of IGF-1 receptor, TbR1, BmpR-1b and Betaglycan in tendon.

<p>Effect of exercise protocols on IGF-1 receptor (<b>A</b>), TbR1 (<b>B</b>), BmpR-1b (<b>C</b>) and Betaglycan (<b>D</b>) mRNA expression in EDL tendon, assessed by real-time PCR. Gene expression is represented as fold-change compared to untrained rats. Data are representative of three independent experiments. *p < 0.05.</p

mRNA levels of IGF-1Ea and TGF-β in tendon.

<p>Effect of exercise protocols on IGF-1Ea (<b>A</b>) and TGF-β (<b>B</b>) mRNA expression in EDL tendon, assessed by real-time PCR. Gene expression is represented as fold-change compared to untrained rats. Data are representative of three independent experiments. *p < 0.05; **p < 0.001.</p

Morphometric results on MTJ complexity.

<p>IL/B ratio (<b>A</b>), maximum insertion depth (<b>B</b>) and Sholl analysis (<b>C</b>) have been evaluated in the MTJs of CTRL, RUN-S and RUN-F. *p < 0.05; **p < 0.01.</p

Morphometric analysis of MTJ complexity.

<p>Morphometric analysis of MTJ base (B) and interface length (IL), and study of muscle-tendon interpenetration (MID) (<b>A</b>). MTJ complexity investigated by means of a modified Sholl analysis (<b>B</b>). m: muscle; t: tendon.</p

Hemodynamic data.

<p>Panel <b>A</b>. Pressure-volume loops obtained in ten consecutive contractions in two representative mice from either group. Panel <b>B</b>. Some hemodynamic data (mean±SEM) obtained in all the examined mice (n=7/6 control and intermittent hypoxia, respectively), * marks P<0.05 with respect to control, Student’s two-tailed t-test. The diastolic (clear) and systolic (shaded) volumes, systolic (clear) and diastolic (shaded) pressures, +dP/dt_max (shaded) and -dP/dt_max (clear), and the cardiac output (clear) are reported.</p

Signaling. Western blots of Akt, its phosphorylated isoform P-Akt, eNOS, its phosphorylated isoform P-eNOS, HIF-1α and Nrf2 in all available samples (mean±SEM, n=6/6 and 5/5 without and with wortmannin, respectively).

<p>*, P<0.05 with respect to control, Student’s two-tailed t-test.</p

Stress proteins.

<p>Panel <b>A</b>. Sample Western blot images illustrating the protein expressions of HO-1, HSP70, GRP94 (referred to α-actin). Panel <b>B</b>. Double immunofluorescence analysis to investigate the nuclear localization of the transcription factor CHOP. The left column shows representative staining using anti-CHOP antibodies (red fluorescence), whereas the middle column shows α−sarcoglycan antibodies (green fluorescence). Nuclei were counterstained with DAPI (blue fluorescence). Arrows indicate cardiomyocyte nuclei positive for CHOP staining, which appears pink when merged with DAPI (right column). The upper and lower rows report a sample control and intermittent hypoxia heart. Bar: 50 µm. Panel <b>C</b>. Quantification of stress proteins from densitometry analysis of Western blots and analysis of Panel B images in all available samples (mean±SEM, n=6/6). *, P<0.05 with respect to control, Student’s two-tailed t-test. This panel also shows the effect of wortmannin on the expression of HO-1 and CHOP (n=5/5).</p