Hypersensitivity of scleroderma cutaneous vascular smooth muscle to 5-hydroxytryptamine.

Vascular smooth muscle strips from subcutaneous wrist vessels of patients with scleroderma (systemic sclerosis) were studied in an isolated system. No difference between catecholamine response of scleroderma or control vessel strips was observed. Three of four patients demonstrated significant hypersensitivity to 5-hydroxytryptamine as compared to control values. Serotonin hypersensitivity may play a role in the evolution of Raynaud's phenomenon and vascular scleroderma.