Introduction: The morphological characteristics of skeletal muscles innervated caudal to a spinal cord injury (SCI) undergo dramatic phenotypic and microvascular changes.
Method: Female Sprague-Dawley rats received a severe contusion at thoracic level 9/10 and were randomly assigned to locomotor training, epidural stimulation, or a combination of the treatment groups (CB). Fiber type composition and capillary distribution were assessed in phenotypically distinct compartments of the tibialis anterior.
Results: Spinal cord injury induced a shift in type II fiber phenotype from oxidative to glycolytic (P < 0.05) as well as capillary loss within the oxidative core and glycolytic cortex; the CB treatment best maintained capillary supply within both compartments.
Discussion: The angiogenic response of CB training improved capillary distribution across the muscle; capillary distribution became spatially more homogeneous and mean capillary supply area decreased, potentially improving oxygenation. There is an important role for weight-bearing training in maintaining the oxidative phenotype of muscle after SCI. Muscle Nerve 59:370-379, 2019.
Keywords: angiogenesis; capillary domain area; epidural stimulation; skeletal muscle; spinal cord injury; treadmill training.
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