Sodium balance studies were performed in chronic Goldblatt type renovascular hypertensive rabbits in order to clarify the mechanism for maintaining the chronic hypertensive states in renovascular hypertension. In two kidney renovascular hypertension, the blood pressure was correlated positively with plasma renin activity and negatively with serum K and faecal Na excretion. Significant correlations were also demonstrated between the latter 3 parameters each other. On the other hand, there was no obvious relationship between the blood pressure and the above parameters in one kidney renovascular hypertension. When the clipped kidney was removed in two kidney type rabbits, a significant fall of blood pressure and significant decreases in hematocrit and Na retention were observed. The fall of blood pressure following the removal of the clipped kidney correlated significantly with the decrease in plasma renin activity, the decrease in hematocrit, the increase in serum K and the increase in faecal Na excretion.
The above observations were interpreted as suggesting a possibility that the increase in plasma renin activity might play an important role in maintaining hypertension in two kidney renovascular hypertension, especially in those with marked elevation of the blood pressure. However, the evidences were not obtained that either renin-angiotensin system or one kidney renovascular hypertension.