Secretion of atrial and brain natriuretic peptides from human cardiac atrial explants in culture: effect of dynorphin.

We have previously developed a method for maintaining human cardiac explants in culture under serum-free conditions, for the assessment of cardiac endocrine function and myocardial growth factors. In order to assess the local role of dynorphin in the human heart, we studied the effects of dynorphin on the secretion of atrial natriuretic peptide and brain natriuretic peptide by human cardiac atrial explants. Dynorphin did not affect the basal secretion of brain natriuretic peptide, but clearly enhanced the release of atrial natriuretic peptide from the human cardiac explants in culture. The atrial content of brain natriuretic peptide was not significantly reduced, whereas the atrial content of atrial natriuretic peptide in cultured explants was reduced two-fold in the presence of dynorphin. These findings indicate that dynorphin may have a direct stimulatory effect on the release of atrial natriuretic peptide, but not brain natriuretic peptide, from human cardiac atria.