B-TYPE AND C-TYPE NATRIURETIC PEPTIDES MODIFY NOREPINEPHRINE UPTAKE AND RELEASE IN THE RAT ADRENAL-MEDULLA

We have previously reported that atrial natriuretic factor (ANF) modul ates adrenomedullar norepinephrine (NE) metabolism. On this basis, the aim of the present work was to study the effects of B and C types nat riuretic peptides (BNP and CNP) on the uptake, intracellular distribut ion and release of H-3-NE. Experiments were carried out in rat adrenal medulla slices incubated ''in vitro.'' Results showed that 100 nM of both, CNP and BNP, enhanced total and neuronal NE uptake. Both peptide s (100 nM) caused a rapid increase in NE uptake during the first minut e, which was sustained for 60 min. NE intracellular distribution was o nly modified by CNP (100 nM), which increased the granular fraction an d decreased the cytosolic pool. On the other hand, spontaneous as well as evoked (KCl) NE release, was decreased by BNP and CNP (50 and 100 nM for spontaneous release and 1, 10, 50 and 100 nM for evoked output) . The present results suggest that BNP and CNP may regulate catecholam ine secretion and modulate adrenomedullary biological actions mediated by catecholamines, such as blood arterial pressure, smooth muscle ton e, and metabolic activities. (C) 1997 Elsevier Science Inc.