Interaction between atrial natriuretic factor and angiotensin II receptors in the regulation of blood pressure.

Atrial natriuretic factor (ANF) and angiotensin II (Ang II) appear to act as physiological antagonists in the regulation of blood pressure and fluid homeostasis. After 18 h incubation in cultured vascular smooth muscle cells, Ang II (10(-8) mol/l) induced down-regulation of ANF receptors (reduced by 60% of total binding capacity) that was inhibited by Sar1-Ile8-Ang II (10(-7) mol/l), whereas ANF (10(-8), 10(-7) mol/l) was not able to affect Ang II receptors. The down-regulation provoked by Ang II was associated with an enhancement of ANF-stimulated cyclic (c) GMP formation and was confined to the non-guanylate cyclase-coupled ANF receptor subtype. This suggests that the decrease in ANF receptors elicited by Ang II and the paradoxical increase in the biological activity of ANF may represent a mechanism that represses excessive or long-term pressor effects of Ang II.