Brain natriuretic peptide is synthesized in the human adrenal medulla and its messenger ribonucleic acid expression along with that of atrial natriuretic peptide are enhanced in patients with primary aldosteronism.

Abstract

The present study was designed to determine whether brain natriuretic peptide (BNP) is synthesized in the human adrenal gland and, if so, to investigate the BNP content of adrenal tissue and the changes in BNP messenger ribonucleic acid (mRNA) in patients with primary aldosteronism. A considerable amount of BNP-like immunoreactive substances was extracted from the adrenal glands of kidney donors for transplantation (0.21 +/- 0.02 pmol/g wet tissue; n = 3) and the remnant nontumorous adrenal glands of patients with primary aldosteronism (0.20 +/- 0.05 pmol/g wet tissue; n = 3; mean +/- SEM). Immunohistochemical study with a specific antihuman BNP antibody revealed that BNP-like immunoreactivity was localized in the adrenal medullary area, and an in situ hybridization study indicated that the BNP mRNA was mainly expressed in the cells of adrenal medulla. Using a reverse transcription and polymerase chain reaction technique, BNP complementary DNA was cloned from the human adrenal gland, and the sequence was identical to that of BNP identified in the atria. The level of BNP mRNA in the adrenal glands of patients with primary aldosteronism (n = 4) was obviously elevated compared to that in the kidney donors (n = 4), as determined by Northern blot analysis. Quantitative polymerase chain reaction measurements of BNP and atrial natriuretic peptide (ANP) mRNAs showed that both of the adrenomedullary natriuretic peptide gene transcriptions were enhanced in patients with primary aldosteronism, but the amount of ANP mRNA was far higher than that of BNP mRNA in the human adrenal gland. Our results are the first to indicate that BNP is synthesized in the human adrenal medulla, and that such medullary BNP synthesis increases in patients with primary aldosteronism. These facts support the proposal that adrenomedullary BNP along with ANP may play some role in water and electrolyte homeostasis or act in a paracrine manner to regulate adrenocortical functions.