Hyperlipidemia and erectile dysfunction.

We have done consecutive studies to investigate the effects of impaired lipid metabolism on the contractile and relaxation response of cavernous smooth muscles and to elucidate its pathogenesis: 1) incidence of hyperlipidemia in impotent patients; 2) erection response to intracavernous injection of papaverine in impotent patients with hyperlipidemia; 3) relaxation responses of isolated cavernosal smooth muscles to endothelium-independent and endothelium-dependent vasodilators in impotent patients with hypercholesterolemia or hypertriglyceridemia; 4) involvement of superoxide radical in the impaired endothelium-dependent relaxation of cavernous smooth muscle in hypercholesterolemic rabbits; 5) effects of isolated lipoproteins and triglyceride, combined oxidized LDL plus triglyceride, and combined oxidized LDL plus HDL on contractile and relaxation response of rabbit cavernous smooth muscles; 6) involvement of e-NOS in the impaired endothelium-dependent relaxation of cavernous smooth muscle in hypercholesterolemic rabbit. Hypercholesterolemia may cause impairment of endothelium-dependent relaxation. Oxidized LDL is the major causative cholesterol of the impaired relaxation response. A chain reaction, the production of superoxide radicals and functional impairment of eNOS may be a major cause of the functional impairment in the early stages of hypercholesterolemia.