Parameters of Blood Flow in Great Arteries in Hypertensive ISIAH Rats with Stress-Dependent Arterial Hypertension
Fractional distribution of86Rb injected intravenously was used to determine the distribution of cardiac output in unanesthetized, unrestrained rats. Renal hypertension was induced by two different methods: severe hypertension was produced by bilateral clamping of the renal arteries (Goldblatt hypertension) and moderate hypertension by kidney encapsulation with collodion followed by contralateral nephrectomy. The distribution of cardiac output was determined 5 or 10 weeks after the production of hypertension. In Goldblatt hypertensive rats the pattern of distribution was very similar after 5 or 10 weeks. On the average fractions of cardiac output were increased by 70% in heart and aorta, by 60% in the colon, by 20–30% in bronchial arteries. A 20–30% reduction was observed in the skin and a 10–20% in the liver. In collodion hypertensive rats similar directional changes were observed but they were of smaller importance. In hypertensive animals the relative enhancement of myocardial blood flow, which reflects the enlarged nutritional demand of the heart, was partly due to cardiac hypertrophy. Nevertheless, the fraction of cardiac output received by 1g of myocardium was increased by 25%. The pattern of redistribution of blood flow indicates that changes in peripheral resistances induced by hypertension are of unequal importance in the different regional beds.