Effect of porcine brain natriuretic peptide (pBNP) on human adrenocortical steroidogenesis

Porcine brain natriuretic peptide (pBNP), purified from porcine brain, had a significant suppressive effect on aldosterone and cortisol secretions in ACTH-treated cultured human adrenal cells. Concomitantly, the intracellular cGMP formation was enhanced by pBNP treatment. A specific pBNP receptor was identified in the human adrenal tissues. Affinity labelling of 125I-pBNP showed two separate molecular weights of specific binding sites for pBNP of 140 and 67 kDa. A 125I-pBNP binding study of the human adrenal membrane fraction demonstrated the presence of high-affinity and low-capacity binding sites for pBNP. Moreover, these binding sites for 125I-pBNP were displaced by unlabelled alpha-rANP as well as pBNP. From these studies, we concluded that pBNP had suppressive effects on human adrenocortical steroidogensis, possibly via a receptor which may be shared with ANP.