Hypersensitivity to noradrenaline in human omental vein but not artery isolated from a patient with idiopathic orthostatic hypotension.

We investigated the smooth muscle contraction in response to noradrenaline (NA), endothelin-1 (ET) and 5-hydroxytryptamine (5-HT) in the omental artery and vein segments from a 67-year-old woman with idiopathic orthostatic hypotension. The blood vessels were obtained during the abdominal surgery and investigated in vitro. Noradrenaline, endothelin-1 and 5-hydroxytryptamine all induced a contraction in the artery and vein segments. Compared to the literature, the sensitivity to noradrenaline was 10 times higher than expected in the vein. In the artery, the sensitivity to noradrenaline and in both the artery and vein, the sensitivity to endothelin-1 and 5-hydroxytryptamine was similar to that reported in the literature. These results suggest that the patient had developed an isolated hypersensitivity to noradrenaline in the veins, probably due to an impairment of the sympathetic activity.