Cardiovascular effects of XXXX in intact awake @entity35 .

@entity35 @entity1831 @entity1808
1. In this study we evaluated, in intact awake @entity35 , the effects of @entity1808 (AII) and vasopressin ( @entity1831 ) on venous tone to explain their different hemodynamic effects. 2. Cardiac index (CI) was measured by thermodilution. AII and @entity1831 were infused at the doses adjusted to increase mean arterial pressure 25, 50 and 70% above baseline. Lower doses of @entity1831 than AII were necessary to increase mean arterial pressure at the same levels. 3. To study whether the different effects of AII and @entity1831 on CI may be explained by their different actions on the venous system, changes in venous tone were evaluated by measuring mean circulatory filling pressure (MCFP) and determining the pressure gradient for venous return (PGVR). 4. @entity1831 induced a decrease in CI from 32.5 +/- 2.2 to 23.1 +/- 1.7 and 15.4 +/- 0.8 ml/min/100 g (P < 0.01) with the second and third level of increase in afterload respectively, whereas AII at the same levels of afterload decreased CI from 34.8 +/- 1.3 to 28.3 +/- 2.3 and 23.4 +/- 1.7 ml/min/100 g (P < 0.01). Furthermore, the rise in total peripheral resistances (TPR) was greater with @entity1831 than with AII at the highest level of afterload (P < 0.05). Heart rate significantly decreased more in the animals infused with @entity1831 than with AII. 5. There were no changes in MCFP and PGVR with either AII or @entity1831 . 6. These results indicate that in intact awake @entity35 the larger fall in CI induced by @entity1831 can not be explained only by a greater decrease in HR since at highest levels of afterload @entity1831 decreased SV.(ABSTRACT TRUNCATED AT 250 WORDS)
