Effect of Angiotensin Infusion on Regional Blood Flow and Regional Vascular Resistance in the Rat

The effects of infusions of angiotensin of 0.05 to 0.5 µg./Kg./min. on the cardiac output, arterial blood pressure, and regional blood flow in the rat have been measured. Angiotensin increases the blood pressure without increasing the cardiac output; the total peripheral resistance is increased. Territorial resistances show varying degrees of increase, ranging from the cerebral vascular resistance, which is reduced or unchanged, to the renal vascular resistance, which shows a 100 to 200 per cent increase. The smallest increases in resistance in other organs are seen in the heart and lungs, which are unchanged, and the spleen and adrenal, which show minimal elevations. Larger changes are seen in the carcass, gut, and skin. The overall appearance of the changes in the distribution of blood flow in the animal infused with angiotensin suggests that blood flow is diverted from the kidneys to those organs most concerned with the immediate response of the organism to an emergency.