Introduction: The aim of this study was to investigate if steroids enhance the vasoconstrictive effect of nor-adrenaline on femoral arteries, which may result in femoral head blood flow reduction.

Materials and Methods: Ten male Wistar rats 62 to 88 days of age, 254 to 318 g of body weight, were used. Twenty femoral artery segments were harvested. These arterial segments were mounted as ring preparations on a small vessel myograph for isometric force measurements. The arteries were stimulated cumulatively with noradrenaline before and after incubation with methylprednisolone (5 μg/ml). Isometric wall tension was plotted and quantified by the EC50, the vasoconstrictor concentration resulting in halfmaximal contraction.

Results: The noradrenaline dose-response curve displayed a shift to the left for the steroid group in relation to the controls. This was reflected by a significantly lower EC50 of 9.5*10⁻⁷ M ± 5.1*10⁻⁷ M for the steroid vessels compared to 2.5*10⁻⁶ M ± 1.1*10⁻⁶ M for the control vessels (mean ± SD; p< 0.005).

Discussion: This study showed that incubation with methylprednisolone enhanced noradrenaline-mediated contraction of femoral arteries. Enhanced contraction of femoral arteries can diminish blood flow within the vascular bed supplying the femoral head. This may be a relevant cofactor in the early pathogenesis of steroid-associated femoral head necrosis.