Betamethasone effects on paraquat lung toxicity

Abstract

1. Betamethasone (1 mg/ml) was administered i.v. to adult Wistar rats 3h before paraquat injection (30 mg/ml) and various parameters of lung function were studied to determine the effect of an anti-inflammatory drug in paraquat lung toxicity.

2. Rats treated with both drugs showed not only increases in spontaneous lung chemiluminescence (90%), malondialdehyde formation (40%), migration of PMN cells to the lungs (450%) and lung wet wt (20%), but also the survival times were decreased to 25% at day 7.

3. The data indicate that betamethasone exacerbates the toxic effects of paraquat. The mechanism can be explained in terms of inhibition of phospholipase A₂ activity, which may increase the accumulation of hydroperoxide, produced by paraquat redox cycling upon lipid membranes.