HYALURONAN AND WATER CONTENT IN THE LUNGS OF TERM RABBIT PUPS KEPT IN AIR OR OXYGEN

Abstract

Increased lung water is considered to be an important component in neonatal respiratory distress. In adult respiratory distress increased lung water is accompanied by high levels of hyaluronan concentrations in broncho-alveolar lavage fluid (Am Rev Resp Dis 1989;139:682-87). Little is known about lung hyaluronan content in the perinatal period. In rabbit pups lung hyaluronan concentration decreases just before term and lung water decreases at term (Am J Physiol 1991;260:H1449-54). Data on preterm rabbits have been presented previously (Ped Res 1992;32;635. The present study was undertaken to study the effect of oxygen exposure on lung hyaluronan concentration and lung water in rabbit pups born at term. Some pups were kept in oxygen and some were kept in air. Pups were sacrificed and lungs were taken at an age of 4-6 days. The water content was measured as wet/dry weight, and the hyaluronan concentration with a radiometric assay kit (HA 50, Pharmacia, Uppsala). Results: In the lungs from pups kept in oxygen significantly higher hyaluronan concentrations were seen both at 4 (p<0.001;n = 14) and 6 (p<0.01;n = 17) days of age compared to the lungs from the pups kept in air (n = 15 and 29, respectively). This was accompanied by a higher lung water content (p<0.001) than in pups kept in air at 4 days of age. Conclusion: In term rabbit pups lung hyaluronan concentration and lung water content increase during oxygen exposure.