Distinct structural and functional angiogenic responses are induced by different mechanical stimuli

Area of Science:

• Physiology
• Skeletal Muscle Biology
• Vascular Biology

Background:

• Microcirculation adequacy is crucial for skeletal muscle function and fatigue resistance.
• Capillary remodeling following different angiogenic stimuli may vary in vessel distribution and functional outcomes.
• The comparative effects of overload-induced stretch versus vasodilator-induced shear stress on muscle microcirculation and function are not well understood.

Purpose of the Study:

• To investigate the physiological consequences of two distinct mechanotransductive stimuli on skeletal muscle microcirculation and function.
• To compare capillary remodeling and functional adaptations induced by overload-mediated abluminal stretch (OV) and vasodilator-induced shear stress (prazosin, PR).

Main Methods:

• Experiments involved in situ EDL fatigue resistance testing after 7 or 14 days of intervention.
• Measurements included femoral artery flow, microvascular composition (histology), and oxidative capacity (citrate synthase activity).
• Muscle PO2 was calculated using mathematical modeling.

Main Results:

• Both OV and PR interventions increased the capillary-to-fiber ratio after 14 days.
• Muscle fatigue resistance significantly improved only after overload (OV) at both 7 and 14 days.
• Overload enhanced local capillary supply indices and reduced citrate synthase activity, while prazosin did not alter aerobic capacity markers.

Conclusions:

• Targeted capillary growth stimulated by abluminal stretch is a key factor in improving muscle fatigue resistance.
• Shear stress-induced angiogenesis does not confer beneficial effects on muscle function.
• Increased capillarity alone does not guarantee enhanced muscle performance; the pattern of growth is critical.