Effects of the intracerebroventricular atrial natriuretic factor on angiotensin II or sodium-induced blood pressure elevation and natriuresis.

We examined the effects of intracerebroventricular (i.c.v.) administration of atrial natriuretic factor (ANF) on pressor and natriuretic responses induced by i.c.v. angiotensin II (Ang II) or hypertonic NaCl in conscious male Wistar rats. The i.c.v. artificial cerebrospinal fluid (CSF) or ANF alone did not cause recognizable changes in mean blood pressure (MBP), urinary volume (UV), or sodium excretion (UNaV). The i.c.v. Ang II or 0.6 M NaCl raised MBP, decreased UV, and increased UNaV. When ANF was administered with Ang II, the Ang II-induced changes in MBP, UV, and UNaV were diminished significantly. ANF also opposed the effects of 0.6 m NaCl, though the effect was significant only in the case of blood pressure. Our results indicate that brain ANF may have antipressor and anti-natriuretic roles.