Absence of human brain natriuretic peptide in pheochromocytoma tissue

We demonstrated that a novel natriuretic hormone, brain natriuretic peptide, modestly inhibited the production of cortisol and aldosterone stimulated by ACTH in cultured bovine adrenocortical cells. Moreover, the presence of brain natriuretic peptide was demonstrated in bovine adrenal medulla, suggesting that it may modulate adrenocortical steroidogenesis. Using a specific radioimmunoassay (RIA) for brain natriuretic peptide-26, we confirmed that human cardiac atrial tissues elaborated a considerable amount of brain natriuretic peptide-26-like immunoreactivity (1.00 +/- 0.17 micrograms/g wet weight tissue, n = 3). Its molecular form was similar to that of brain natriuretic peptide-32 and possibly, to gamma-brain natriuretic peptide. However, any immunoreactivity of brain natriuretic peptide could not be detected in human pheochromocytoma tissues and some tissues of the human central nervous system. These observations suggest that brain natriuretic peptide dose not function as a neuropeptide but that it may be a cardiac natriuretic hormone important in human physiology, involved in the balance of water and electrolytes.