[Effect of microinjection of angiotensin II into area postrema on renal sodium excretion]

It has been known that area postrema (AP) possesses angiotensin II (A II) receptors and senses directly the change of blood A II level. The effect of microinjection of A II into the AP on renal sodium excretion was studied in the present investigation. Our experimental results show that microinjection of A II (2, 20 ng) increases GFR, RPF and UNaV (P < 0.05). These changes can be abolished by A II antagonist, saralatin and renal denervation (P < 0.05). However microinjection of A II (20 ng) into NTS produces no such changes. These results strongly suggest that the A II induced changes of renal hemodynamics and urine sodium excretion are mediated through AP.