ENDOTHELIN mRNA EXPRESSION AND ITS LOCALIZATION IN INTRAPULMONARY ARTERIES OF CHRONIC HYPOXIC RATS

To study endothelin-1 (ET-1) gene expression and its distribution in intrapulmonary arteries of chronically hypoxic rats. Methods: in situ hybridization studies were performed onpulmonary arteries in Wistar rats using biotinlabelled cRNA probe for ET-1. Results: Most of intrapulmonary arteries showed ET-1 mRNA positive expression (+) in endothelial cells of either one-week ortwo-week hypoxic rats, whereas only few intrapulmonary arteries did in those of control rats (P＜0.01). Furthermore, some intrapulmonary arteries expressed intense ET-1 mRNA signals (+ +) in endothelial cells. ET-1 was expressed (+) in pulmonary artery smooth muscle cells of either one-week ortwoweek hypoxic rats but no signal was observed in those of controls (P ＜ 0．01 and 0. 05,respectively). Conclusion: Chronic hypoxia alters ET-1 gene transcription mainly in the pulmonaryartery endothelial cells and then smooth muscle cells.