The Effect of Angiotensin-Converting Enzyme Inhibition on Regional Blood Flow in Salt-Depleted and Salt-Loaded Normotensive Conscious Rats

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Abstract
The effect of angiotensinconverting enzyme inhibition on regional blood flow was studied in a total of 21 normotensive Wistar rats fed on either low or high salt diet. A new potent angiotensinconverting enzyme inhibitor (CEI), SQ 14, 225 was administered intravenously in a dose of 2mg/Kg to the conscious animals, and changes in fractional distribution of cardiac output were determined with a microsphere method. Prior to administration of CEI, there was no significant difference in mean arterial pressure (MAP) or regional blood flow between saltdepleted and saltloaded rats. With CEI, MAP did not change significantly in either group. Fractional distribution of cardiac output increased to the kidneys (p<0.002), and decreased to the stomach, spleen, and skeletal muscle (p<0.02, p<0.002, and p<0.01, respectively) in the saltdepleted group, while a pattern of blood flow distribution was not changed in the saltloaded group. These results suggest that angiotensin II plays an important role in regulating regional blood flow in saltdepleted conscious animals, but not in saltloaded ones.