Text Box: A STUDY ON THE ROLE OF AM, ET-1 AND NO IN CHILDREN WITH PULMONARY HYPERTENSION SECONDARY TO CONGENITAL HEARTS DEFECTS WITH LEFT TO RIGHT SHUNT Chen Shaojun, Lu Huiling Medical College of Huazhong University of Science and Technology, HuBei,China Objective: To observe the changes of adrenomedullin (AM), endothelin (ET), nitric oride (NO) levels in congenital hearts defects associated with pulmonary hypertension (PH) and discuss their mechanism and clinical significance. Methods: Levels of plasma AM, ET-1and serum NO metabolites were measured in four group: (1) Non-PH (n=11), pulmonary artery systolic pressure (PASP)<30 mmHg; (2) Light-PH(n=10) PASP≥30mmHg, PASP<50mmHg; (3) medium or heavy-PH (n=12) PASP>50mmHg; (4)healthy control (n=15). Sample was obtained on admission and seventh day after operation. Result: 1. Plasma AM and ET-1 level of PH groups were apparently higher than that non-PH and control group (p<0.01) and the AM and ET-1 level were associated with the severity of PH. Seventh day after operation plasma AM and ET-1 level were decreased, but still higher than control group. 2. Serum NO concentration of PH groups were apparently lower than non-PH group and control group (p<0.05); The seventh day after operation, its level was increased slightly. 3. Plasma AM level correlated positively with PASP and ET-1 (R=0.88, R=0.78, P<0.01) respectively. Conclusion: ET-1 and NO play an important role in the development and the progression of PH in the cases of CHD, the increased AM may interact with NOand ET-1 to help regulate pulmonary circulation in the pathophysiology of PH with CHD. As being a hypotensive peptide, a local antiproliferation and antimigration factor, AM may represent a compensatory mechanism under conditions of increased pulmonary vascular pressure and may be involved in the defence mechanism against further increases in pulmonary arterial pressure. Plasma AM could be used as a reliable indicator of the severe of PH in CHD with left to right shunt. 1063