Distribution of capillaries in normal and diseased human skeletal muscle

The distribution of capillaries was studied in muscle biopsies in a large number of normal subjects and in patients with disuse atrophy, inflammatory myopathies, and other chronic myopathic and neurogenic disorders. The cryostat retrieval technique was used, along with capillary and muscle fiber morphometry, to quantitate capillary distribution around specific fiber types. In all diseased and normal muscle, the number of capillaries per fiber (C/F) and the number of capillaries surrounding a fiber (CAF) increased with fiber diameter. More capillaries typically surrounded type 1 than type 2 fibers within a given group. When all inflammatory myopathy patients (polymyositis, dermatomyositis, and polymyositis plus second connective tissue disease) were compared with normal adults, their muscle biopsies had fewer capillaries per fiber over the same diameter range. The numerous variables influencing capillary number in normal and diseased muscle are discussed.