Influence of atrial natriuretic factor on uptake, intracellular distribution, and release of norepinephrine in rat adrenal medulla.

Abstract

Several studies have demonstrated that atrial natriuretic factor can bind to adrenal medulla cells. Furthermore, atrial natriuretic factor immunoreactivity has been identified in chromaffin cells. The aim of the present work was to investigate atrial natriuretic factor effects on the uptake, intracellular distribution, and release of norepinephrine in the rat adrenal medulla. Results showed that 100 nM atrial natriuretic factor induced a rapid increase of norepinephrine uptake during the first minute of the incubation period. This increase was maintained for up to 60 min. In addition, only neuronal norepinephrine uptake was increased by the natriuretic factor; non-neuronal norepinephrine uptake was unaltered. Atrial natriuretic factor modified the intracellular distribution of the amine store: the granular fraction of norepinephrine increased, while the cytosolic fraction decreased. On the other hand, different concentrations (10, 50, and 100 nM) of the atrial factor decreased spontaneous [3H]norepinephrine output in a concentration-dependent manner. Furthermore, atrial natriuretic factor (10 nM) also reduced high potassium solution evoked secretion of norepinephrine. These results suggest that atrial natriuretic factor modulates sympathetic activity in the rat adrenal medulla. These effects of atrial natriuretic factor may be related to the catecholamine peripheral mechanism involved in the regulation of arterial blood pressure, smooth muscle tone, metabolic activity, etc.