title: Imatinib attenuates monocrotaline pulmonary hypertension and has potent vasodilator activity in pulmonary and systemic vascular beds in the rat.
abstract: Cardiovascular responses to the tyrosine kinase inhibitor imatinib were investigated in the rat. Intravenous injections of 0.3-30 mg/kg imatinib produced small decreases in pulmonary arterial pressure, larger dose-dependent decreases in systemic arterial pressure, and no change or small increases in cardiac output, suggesting that the systemic vasodilator response is more pronounced under baseline conditions. When pulmonary arterial pressure was increased with U-46619 or N(ω)-nitro-L-arginine methyl ester (L-NAME), intravenous injections of imatinib produced larger dose-dependent decreases in pulmonary arterial pressure. Imatinib attenuated the acute hypoxic pulmonary vasoconstrictor response. Vasodilator responses to imatinib were not inhibited by meclofenamate, glybenclamide, or rolipram, suggesting that cyclooxygenase, ATP-sensitive K(+) (KATP) channels, and cAMP were not involved in mediating the response. In a 21-day prevention study, imatinib treatment (50 mg/kg ip) attenuated the increase in pulmonary arterial pressure, right ventricular hypertrophy, and small vessel remodeling induced by monocrotaline. Imatinib reduced PDGF receptor phosphorylation and PDGF-stimulated thymidine incorporation in rat pulmonary artery smooth muscle cells. These data suggest that the beneficial effect of imatinib in pulmonary hypertension may involve inhibition of PDGF tyrosine kinase receptor-mediated effects on smooth muscle cell proliferation and on vasoconstrictor tone. These results indicate that imatinib has nonselective vasodilator activity in the pulmonary and systemic vascular beds similar to the Rho kinase inhibitor fasudil and the calcium entry antagonist isradipine. The present results are consistent with the hypothesis that imatinib may inhibit a constitutively active tyrosine kinase vasoconstrictor pathway in the pulmonary and systemic vascular beds in the rat.
authors.affiliation: Departments of Pharmacology and Medicine (Pulmonary Diseases, Critical Care and Environmental Medicine Tulane University School of Medicine, New Orleans, Louisiana.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Pankey
authors.forename: Supat
authors.initials: S
authors.lastname: Thammasiboon
authors.forename: George F
authors.initials: GF
authors.lastname: Lasker
authors.forename: Syed
authors.initials: S
authors.lastname: Baber
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Lasky
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Kadowitz
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D062186:Arterial Pressure / Q000187:drug effects*; D001549:Benzamides / Q000494:pharmacology*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D006976:Hypertension, Pulmonary / Q000139:chemically induced / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology / Q000517:prevention & control*; D017380:Hypertrophy, Right Ventricular / Q000503:physiopathology / Q000517:prevention & control; D000068877:Imatinib Mesylate; D008297:Male; D016686:Monocrotaline; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology; D058988:Phosphodiesterase 4 Inhibitors / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011651:Pulmonary Artery / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology / Q000503:physiopathology; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017479:Receptors, Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D000959:Antihypertensive Agents; D001549:Benzamides; D016861:Cyclooxygenase Inhibitors; D058988:Phosphodiesterase 4 Inhibitors; D010879:Piperazines; D026902:Potassium Channel Blockers; D047428:Protein Kinase Inhibitors; D011743:Pyrimidines; D014665:Vasodilator Agents; D016686:Monocrotaline; D000068877:Imatinib Mesylate; C099852:PDGF receptor tyrosine kinase; D017479:Receptors, Platelet-Derived Growth Factor
keywords: PDGF; imatinib; pulmonary vascular bed; tyrosine kinase inhibitor; vasodilation