AQUAPORIN-3 IS INDUCED IN RAT ALVEOLAR EPITHELIUM AFTER BIRTH

Aquaporin (AQP) is the water channel protein associated with water-per meability, in which AQP1, AQP3, AQP4, and AQP5, are expressed in respi ratory organs. Because water filling the fetal lung has to be absorbed after birth, aquaporins are postulated to contribute to this water re absorption. To examine the potential role of AQP3 around birth, we stu died mRNA expression and localization of AQP3 in fetal and postnatal r at lung. AQP3 mRNA was most prominently expressed in rat lung on the d ay of birth, began to decrease on the 2nd day after birth, and was not observed on the 4th day and later. In situ hybridization demonstrated that AQP3 mRNA was expressed in alveolar epithelium. The expression o f AQP3 mRNA may influence water reabsorption of the perinatal rat lung .