Angiogenic effect of intramuscular administration of basic and acidic fibroblast growth factor on skeletal muscles and influence of exercise on muscle angiogenesis.

BACKGROUND Angiogenic factors which control the angiogenic process represent a promising strategy for restoration of blood flow, but require further evaluation before clinical use. Exercise has also been reported to induce neovascularisation in muscles. OBJECTIVES To evaluate the angiogenic effects of basic fibroblast growth factor (b-FGF) and acidic fibroblast growth factor (a-FGF) on rat gastrocnemius muscle, when administered intramuscularly, and to compare them with those obtained by daily exercise. METHODS Forty nine rats were allotted to the following groups: A, controls; B, exercise by swimming; C1 and C2, intramuscular injection of b-FGF and a-FGF respectively; D1 and D2, b-FGF and a-FGF injection in combination with exercise. The antibody mouse anti-rat CD31 was used to evaluate the numbers of blood vessels present in histological preparations of gastrocnemius muscle. RESULTS Significant increases in the numbers of blood vessels of the right gastrocnemius muscles in groups C1 and D1 were observed compared with controls (p<0.05). There was only a slight increase in angiogenesis in the left gastrocnemius muscle of groups C1 and D1 compared with controls (p>0.05), and there was a decrease in angiogenesis in the gastrocnemius muscle of the swimming group compared with controls. CONCLUSION The intramuscular administration of b-FGF, but not a-FGF, induced significant local angiogenesis in gastrocnemius muscle at the site of injection.