Comparative effects of bradykinin and atrial natriuretic factor on neuronal and non-neuronal noradrenaline uptake in the central nervous system of the rat

Abstract

Binding sites of atrial natriuretic factor (Anf) and bradykinin (Bdk) have been described in discrete areas of central nervous system of the rat. The interaction between Anf and Bdk on noradrenaline (Na) uptake were studied in hypothalamus (Hyp) and medulla oblongata (Mo).

One hundred nM Anf in both regions and 100pM Bdk in Hyp and 1 nM Brd in Mo in-creased total Na uptake. Subthreshold concentrations of Anf (1 nM) reversed the effect of threshold concentrations of Bdk in Hyp and Mo. Non-effective concentrations of Brd did not modify the increase produced by 100nM Anf in both central regions. Effective concentrations of Anf and Bdk did not induce additive effect in total ³H-Na uptake neither in Hyp nor in Mo. Threshold concentrations of Anf and Bdk increased only neuronal Na uptake in Hyp as well as Mo.

These results suggest an Anf-Bdk interaction at the neuronal Na control mechanisms involved in the regulation of blood pressure, electrolytes and water balances, and neuroendocrine processes.

Key Words:

• hypothalamus
• medulla oblongata
• Na uptake
• bradykinin
• Anf
• rat