Adrenergic responses in human small arteries isolated from the femoral neck.

Many pathological bone conditions are accompanied by changes in bone perfusion. However, no method has yet allowed investigation of vascular reactivity in human bone tissue. In the present study, arterial segments (diameter approximately 0.25 mm) were isolated from human bone biopsies and mounted as ring preparations in vitro. The viability of the arteries and the effects of adrenoceptor stimulations were investigated. Combined alpha- and beta-adrenoceptor stimulation (noradrenaline 10(-8)-10(-5) M) and specific alpha1-adrenoceptor stimulation (phenylephrine, 10(-8)-10(-4.5) M) induced concentration-dependent contractions in all arteries. Selective stimulation of alpha2-receptors (B-HT 933, 10(-8)-10(-3.5) M) only induced contraction in three of eight arteries. Stimulation of beta-receptors with isoprenaline (10(-6) M) resulted in vasorelaxation in 3 of 10 arteries. In all arteries, acetylcholine (10(-10)-10(-5) M) induced vasorelaxation, demonstrating preserved function of the endothelium. The results suggest that primarily alpha1-receptors are responsible for adrenoceptor induced vasoconstriction in human bone while functional alpha2- and beta-receptors may not be consistently expressed. The model is the first to allow investigations on vascular reactivity in human bone tissue and may become valuable for assessment of both normal and pathological bone physiology.