Vascular effects of angiotensin and norepinephrine in the dog, cat, and monkey

Abstract

The direct effects of angiotensin and norepinephrine on forelimb vessels were compared in the dog, cat, and monkey in constant-flow forelimb preparations. Equiweight and equimolar injections and in some instances equiweight infusions were carried out. Brachial artery pressure (BAP), small vein pressure (SVP), and limb weight changes were continuously recorded. In some instances, intact, natural-flow preparations were employed. With equimolar injections in constant-flow limbs, angiotensin increased limb BAP and SVP more than norepinephrine in the dog and cat, and caused a significantly greater loss of limb weight in the dog. With equiweight doses, angiotensin caused a greater increase of cat forelimb BAP and SVP and monkey SVP; norepinephrine injection resulted in a greater increase of dog limb BAP and SVP and approximately the same increase of monkey BAP as angiotensin. Limb weight loss was not significantly different in any species. The initial SVP elevations produced by angiotensin and norepinephrine infusion were about equal, but the small veins became unresponsive to angiotensin after several minutes of infusion.