The effect of dietary restriction and altered sodium intake on the cardiopulmonary toxicity of monocrotaline pyrrole.

Monocrotaline pyrrole (MCTP) is a reactive metabolite of the plant toxin monocrotaline (MCT), which produces pulmonary vascular injury and right ventricular hypertrophy in rats. In this study, the influence of diet restriction on the cardiopulmonary toxicity of MCTP was examined. In rats fed ad libitum, MCTP treatment resulted in increased lung weight, in elevated lactate dehydrogenase (LDH) activity and protein concentration in cell-free bronchopulmonary lavage fluid, and in right ventricular enlargement. Restriction of feed intake to 40% of normal attenuated the increases in lung weight and lavage protein concentration in MCTP-treated rats and abolished the right ventricular enlargement but did not affect the increased lavage LDH activity. In a study of the effect of diet restriction on the survival of MCTP-treated rats, the percentage of diet-restricted animals surviving was significantly higher than that of surviving animals which ate ad libitum through Day 28, but thereafter there was no significant difference between the two groups. Alterations in dietary sodium intake alone did not affect MCTP-induced toxicity. These results indicate that diet restriction partially protects against the cardiopulmonary toxicity due to MCTP, and that this protective effect cannot be explained by changes in salt intake.