Angiotensin II AT, receptor mediated contraction of the perfused rat cerebral artery

The effect of angiotensin II on rat cerebral arteries was studied using isolated, perfused segments of anterior cerebral arteries. The infusion rate was set to maintain baseline intraluminal pressure at 75 mmHg. Angiotensin II (100 nM) increased the intraluminal pressure by 22.5 +/- 2.2 mmHg. Losartan, an AT1 antagonist, at 1 microM, completely blocked the effect of angiotensin II, whereas the AT2 ligands PD 123319 (1 microM) and CGP 42112 (1 microM) were ineffective. None of these AT1 or AT2 selective ligands alone displayed any agonist effects. The results show that angiotensin II induces contraction of the rat anterior cerebral artery by acting on AT1 receptors.