Alteration of monocrotaline pyrrole‐induced cardiopulmonary effects in rats by hydralazine, dexamethasone or sulphinpyrazone

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Abstract
1 The effects of intraperitoneal hydralazine, dexamethasone, or sulphinpyrazone on the toxicity of monocrotaline pyrrole (MCTP) were examined in rats 14 days after injection of MCTP (5 mg kg−1, i.v.). 2 MCTP alone caused increases in lung weight, and of both lactate dehydrogenase activity and protein concentration in bronchopulmonary lavage fluid. Right ventricular hypertrophy also occurred. 3 Hydralazine (3 mg kg−1, daily), a vasodilator and platelet prostaglandin synthesis inhibitor, reduced the degree of right ventricular hypertrophy and the elevation in the concentration of protein in lavage fluid. 4 Dexamethasone (27 μg kg−1, daily), an anti-inflammatory agent and inhibitor of phospholipase, also reduced the right ventricular hypertrophy and the increased protein concentration in lavage fluid caused by MCTP. 5 Sulphinpyrazone (100 mg kg−1, twice daily), an inhibitor of platelet prostaglandin biosynthesis, prevented right ventricular hypertrophy in the MCTP treated rats without affecting any of the indices of lung injury. 6 These results provide further support for the hypothesis that platelets and vasoconstrictor agents play a role in the development of MCTP-induced pulmonary hypertension.