Text Box: THE LEVEL AND EXPRESSION OF ENDOTHELIN-1 (ET-1) AND CALCITONIN GENE-RELATED PEPTIDE (CGRP) IN THE LUNG OF PULMONARY HEMORRHAGE OF NEWBORN RAT INDUCED BY HYPOTHERMIA AND HYPOXIA Wang W,Chen KZ, Lu H,Chen GH Guangzhou Children's Hospital, Guangzhou, P.R. China Objective: To establish the reasonable pulmonary hemorrhage (PH) model of newborn rat and explore the possible relationship between PH. and ET-1、calcitonin-gene related peptide (CGRP). Methods: Wistar newborn rat were randomly divided into normal (group A); hypothermia and hypoxia for 1h ( group B); 2h(group C); 4h (group D); the last three groups were all followed by rapid rewarming and reoxygenation for 2h. The optimal experimental condition resulted in PH was testified by HE staining and transmission electronic microscope. The level of and expression of ET-1 and CGRP in the lung of PH and control group were measured by radioimmunoassay and immuno histochemical method. Results: The pathological injury in the group D was more coincident with PH than that in group B and C. The level of ET-1 and CGRP in lung of PH markedly increased compared with control (P<0.001). There was positive or strongly positive staining of ET-1 and CGRP in PH while control appeared negative or mild positive. There was significant difference in the staining of ET-1、CGRP between PH and normal. Conclusion: The PH model of newborn rat coincident with the clinical tiology could be established by hypothermia. And hypoxia for 4h followed by rapid rewarming and reoxygenation for 2h. The abnormal elevating level and expression of ET-1 in lung are possibly involved in the pathology of PH. 0349