INCREASED PLASMA ADRENOMEDULLIN CONCENTRATIONS DURING CARDIAC-SURGERY

1. Adrenomedullin(AM), a potent hypotensive peptide, was originally is olated from human phaeochromocytoma, Plasma AM concentrations are elev ated in hypertension, heart failure and renal failure in proportion to the severity of the disease. This study was performed to investigate the pathophysiological significance of AM during cardiac surgery, 2. S erial blood samples were obtained from patients undergoing cardiac sur gery and plasma AM concentrations were determined by specific radioimm unoassay, 3. Plasma AM concentrations did not increase with anaesthesi a or surgery (n = 9), Plasma AM concentrations gradually increased dur ing cardiopulmonary bypass and after pulmonary reperfusion, After pulm onary reperfusion, plasma AM concentrations increased further. In addi tion, we measured plasma AM concentrations in the pulmonary vein (n = 8) and coronary sinus (n = 8) to examine the contribution of the lungs and heart to the increase in circulating AM concentrations after card iopulmonary bypass. However, no significant differences were seen in p lasma AM concentrations of the pulmonary vein or the coronary sinus an d the aorta, Peak AM concentrations during cardiac surgery correlated with duration of surgery. Elevated plasma AM levels during and after s urgery began to decline next day after surgery and returned to normal levels 7 days after surgery.4. These results demonstrate that plasma A M concentrations increase during cardiac surgery and that the duration of surgery may be related to the changes in AM concentrations. Taken together with recent findings that vascular endothelial cells and vasc ular smooth muscle cells actively produce AM, these results suggest th at plasma AM during cardiac surgery may act as a vasodilatory hormone.