AIM: To investigate the effect of elevated basal shear stress on angiogenesis in humans, and the role of enhanced skeletal muscle capillarisation on blood flow and O2 extraction.

METHODS: Limb haemodynamics and O2 extraction was measured at rest and during one-leg knee-extensor exercise (12 and 24W) in 10 healthy untrained young men before and after 4 weeks treatment with an α1 receptor-antagonist (Terazosin, 1-2 mg day(-1) ). Corresponding biopsies were taken from the m. vastus lateralis.

RESULTS: Resting leg blood flow was increased by 57% 6 hours following Terazosin treatment (P<0.05), while basal capillary-to-fibre ratio was 1.69±0.08 and increased to 1.90±0.08 after treatment (P<0.05). Leg O2 extraction during knee-extensor exercise was higher (4-5%; P<0.05), leg blood flow and venous lactate levels lower (6-7%; P<0.05), while leg VO2 was not different after Terazosin treatment.

CONCLUSIONS: These results demonstrate that daily treatment with an α-adrenergic receptor blocker induces capillary growth in human skeletal muscle, likely due to increased shear stress. The increase in capillarisation resulted in an increased fractional O2 extraction, a lower blood flow and venous lactate levels in the exercising leg. The increase in capillarisation, and concomitant functional readouts in the exercising leg, may provide a basis for novel angiotherapy. This article is protected by copyright. All rights reserved.