Chronic one-kidney hypertension in rabbits. I. Treatment with kidney extracts

An investigation into the mechanism that sustains the blood pressure in chronic one-kidney hypertension in rabbits was made using passive and active immunization with hog kidney extracts containing renin and with angiotensin antagonists. Seven hypertensive rabbits were passively immunized for extended periods with antiserum prepared in other rabbits. Antirenin levels were in the range of 1-3 units/ml. Control experiments demonstrated that antirenin concentrations of 1.0 unit/ml or more eliminated more than 99% of the pressor response to renin. There was no lowering of blood pressure that could be attributed to the antibodies. No decrease in blood pressure was observed in 13 experiments in 7 rabbits given the angiotensin II antagonist 1-Sar-8-Ile-angiotensin II; infusion rates of 0.09-87 mug/min kg-1 were used for periods of a few hours up to 3 days. A reduction in blood pressure occurred in 16 of 19 rabbits immunized directly with extracts containing renin with specific activities of 9.6-757 GU/mg. Plasma antirenin titers correlated poorly with reductions in blood pressure. The blood pressure of 22 rabbits given equal amounts of protein without renin was unaffected. It is concluded that the elevation of blood pressure in rabbits with chronic one-kidney hypertension is not dependent on ciculating renin or angiotensin; rather, it results from the presence of renin in an extravascular location or from an unknown pressor substance.