Release of neuropeptide Y and hemodynamic changes during surgical removal of human pheochromocytomas

This study investigates the release of Neuropeptide Y from eight human pheo chromocytomas. Profil immunoreactive Neuropeptide Y (Ir-NPY) levels during the management of surgery were compared with these of norepinephrine (NE) w hile hemodynamics were monitored. Plasma IrNPY and NE levels increased duri ng tumor manipulation and returned to near normal one hour after operation. However, Ir-NPY levels remained high just after tumor resection while NE l evels were significantly decreased. At tumor manipulation and just after tu mor resection, plasma Ir-NPY levels were correlated with the systemic vascu lar resistances (SVR) (r = 0.74; P < 0.04 and r = 0.86; P < 0.006 respectiv ely). No correlation was found either between plasma Ir-NPY and NE levels o r between plasma NE levels and SVR. The release of Ir-NPY from tumor tissue , studied by a superfusion method, exhibited a significant correlation with the plasma Ir-NPY concentrations at the time of corresponding tumor resect ion (r = 0.95; P < 0.007). Chromatographic analysis showed that Ir-NPY in p lasma and outflow migrate as human NPY(1-36). These results confirmed that in pheochromocytoma, plasma NPY mainly originates from the tumor and argue for an important role of NPY in pheochromocytoma hypertension as indicated by the correlation between the Ir-NPY levels and the SVR. (C) 2000 Elsevier Science B.V. All rights reserved.