Figure 4.

Increased platelet aggregation and apoptosis in β1β2M-KO TA muscles. A) A significant increase in platelet aggregation, as measured by the ratio of CD41-positive to PECAM-positive, was observed in β1β2M-KO (M-KO) TA muscles compared to WT. Right panel is a representative immunofluorescent stain of WT and β1β2M-KO muscle cross sections with PECAM (green) labeling all capillaries and CD41 (red) labeling platelet aggregates. B) Representative images of TUNEL staining in WT and β1β2M-KO TA muscles. TUNEL-positive areas (red, left panels) were overlaid with DAPI (blue, right panels) to ascertain the number of apoptotic nuclei (yellow arrows, apoptotic interstitial nuclei; yellow arrows with asterisk inside, apoptotic myonuclei). Insets highlight TUNEL-positive, DAPI-positive nuclei that are within the myofiber (m) or outside of the myofiber (e), presumably capillaries. C) Quantification of the TUNEL-positive nuclei within the TA reveals a significant increase in apoptotic nuclei within the muscle (as would be expected in myopathic muscles) and an even more robust difference in TUNEL-positive nuclei that were outside of the muscle fiber (nonmyonuclei) in the β1β2M-KO TA. D) Alkaline phosphatase stain in WT and β1β2M-KO TA muscles. Left panel: quantification of capillary density as percentage of WT values demonstrates significantly lower capillary density in TA muscles of β1β2M-KO mice (∼45%) compared to WT. Right panel: representative images. Data are expressed as means ± se; n = 4–8. Scale bars = 50 μm. *P < 0.05 vs. WT.