Atrial Natriuretic Factors Inhibits of Noradrenaline Biosynthesis, Utilization and Turnover Rate

pp 625-630

Abstract

We have previously reported changes in norepinephrine (NE) uptake and release induced by atrial natriuretic factor (ANF). These modifications maybe associated with modifications in the synthesis and turnover of the amine. On these basis the aim of the present work was to study the effects of atrial natriuretic factor (ANF) on the endogenous content, utilization and turnover of NE, tyrosine hydroxylase (TH) activity, and second messenger generation in the rat hypothalamus.

Results showed that ANF (100 ng/μl, intracerebroventricular administration) increased the endogenous content of NE (by 45%) and diminished the amine utilization and turnover (53%). In addition, the ANF (10 nM) inhibited both basal as well as KCl-evoked TH activity (30% and 64% respec-tively). On the other hand, 10 nM ANF increased cGMP levels (110%), whithout modifying either cAMP accumulation or phophatidylinositol hydrolysis.

These results suggest that ANF may play an important role in the hypothalamic noradrenergic neurotransmission as a putative modulator. Thus, the atrial factor may be involved in the regulation of several central and peripheral physiological processes such as, the cardiovascular activity, electrolyte and fluid homeostasis, endocrine and neuroendocrine synthesis.