Decreased inactivation of prostaglandin E2 in isolated lungs from rats with alpha-naphthyl thiourea-induced pulmonary oedema.

The effect of pulmonary oedema on the pharmacokinetic function of rat lungs was studied using prostaglandin E2 (PGE2) as substrate; oedema was induced by alpha-naphthyl thiourea (ANTU). Male rats were given a single i.p. injection of ANTU (10 mg/kg). Lung wet weight, dry:wet weight ratio and pleural transudate were measured at fixed times up to 50 hr after treatment. Wet weight was increased after 4 hr and remained higher than controls until 50 hr; dry:wet weight ratios were different only at 6 and 16 hr. Survival of PGE2 (measured by bioassay) was increased at 4 hr, reached a peak value of about six times the control survival at 6 hr and returned to normal by 50 hr. Using 14C-PGE2 as substrate, survival was maximal at 16 hr and back to normal by 50 hr. The efflux profiles of radioactivity showed an increase in T1/2 by 4 hr rising to a maximum at 28 hr and a normal value at 50 hr. Changes in PGE2 survival precede the period of oedema (assessed by dry:wet ratio) and could be used as an early warning of oedematous states. This altered pharmacokinetic function of lung could also have systemic effects.