Abstract 81

Background. Aspiration of meconium produces a severe respiratory distress, characterized by inflammatory reaction in the lung tissue. Aspirated meconium stimulates alveolar macrophages to produce proinflammatory mediators, supposedly also prostaglandins. To study this activation we investigated the effects of intratracheal meconium on the expression of cyclooxygenase-1 and -2 (cox-1 and -2) in rat lungs.

Material. Sixteen anesthetized rats, ventilated with either synthetic air (N=12) or 100% oxygen (N=4) were studied.

Interventions. A bolus (3 ml/kg) of 20% human meconium solution was administered intratracheally in 12 rats, while four control rats received an equal volume of sterile saline. Three hours after instillation of meconium or saline the lungs were removed and the amount of cox-1 and -2 mRNA was analyzed by northern blot hybridization.

Results. Cox-1 mRNA was clearly expressed in the control lungs, while cox-2 expression was minimal. Meconium administration did not affect the expression of cox-1, but cox-2 mRNA expression was upregulated both in lungs ventilated with air or oxygen.

Conclusions. Our data indicate that intrapulmonary human meconium induces upregulation of lung cox-2 gene expression suggesting an important role for prostaglandins in the meconium aspiration-induced pulmonary inflammation.