ENDOTHELIN-1 INDUCED VASCULAR SMOOTH MUSCLE CELL PROLIFERATION IS MEDIATED BY CYTOCHROME P-450 ARACHIDONIC ACID METABOLITES

Endothelins (ETs) are a family of three peptides (ET-1, ET-2, ET-3) that are implicated in the physiological control of vascular smooth muscle cell (VSMC) and myocardial contractility and growth. ET-I is vasoactive peptide that acts via ET-A receptors coupling inducing vascular smooth muscle cell contraction. ET-1 is involved in the development and maintenance of hypertension. Aim of this study was to investigate whether ET-1 can induce vascular smooth muscle cell proliferation through arachidonic acid (AA) metabolites formed via cytochrome P-450 (CYP-450). VSMC proliferation was measured by [H-3]thymidine incorporation in cultured cells treated by ET-1 (10 to loo nmol/L) in presence of different inhibitors of CYP-450 (17-ODYA 5 mu mol/L), lipoxygenase (LO) (baicalein 20 mu mol/L) and cyclooxygenase (COX) (indomethacin 5 union). ET-1 (10 to 100 nmol/L) induced VSMC proliferation and this effect was attenuated by CYP-450 inhibitor (17-ODYA) and lipoxygenase (LO) inhibitor (baicalein) but not by cyclooxygenase (COX) inhibitor (indomethacin). CYP-450 and LO metabolites of AA, 20-hydroxyeicosatetraenoic acid (HETE) and 12-HETE increased [H-3]thymidine incorporation in VSMC. Inhibitors of MAP kinase (PD-98059 50 mu mol/L and cPLA(2) (MAFP 50 mu mol/L) attenuated ET-1 as well as 20-HETE induced VSMC proliferation. These results suggest AA metabolites via CYP-450 mediates ET-1 induce VSMC proliferation.