Effect of atriopeptin on blood flow to cerebrum and choroid plexus.

The goal of this study was to determine whether atriopeptin alters blood flow to cerebrum and choroid plexus. In anesthetized rabbits, blood flow (microspheres) to cerebrum and choroid plexus under control conditions was 36 +/- 3 (mean +/- SE) and 573 +/- 78 ml.min-1.100 g-1, respectively. Infusion of atriopeptin (75, 225, 1,150 ng.kg-1.min-1 iv) increased blood flow to choroid plexus by 22 +/- 11, 53 +/- 26, and 51 +/- 13%, respectively. In contrast, blood flow to cerebrum was not altered by atriopeptin, presumably because the blood-brain barrier prevented access to cerebral vascular smooth muscle. Because a major role of atriopeptin may be to modulate responses to angiotensin II, we examined effects of atriopeptin on vasoconstrictor responses to angiotensin II in the choroid plexus. Angiotensin II was infused in the presence or absence of atriopeptin (300 ng.kg-1.min-1 iv). Angiotensin II (100 ng.kg-1.min-1 iv) decreased blood flow to choroid plexus by 49 +/- 12% and by 47 +/- 14% during simultaneous infusion of atriopeptin. In summary, atriopeptin 1) increases blood flow to choroid plexus, but not cerebrum, and 2) does not appear to attenuate vasoconstrictor effects of angiotensin II in the choroid plexus.