Abstract
A radioimmunoassay method for ileu-5-angiotensin I was applied to the measurement of plasma renin in rabbits. In the present method, the volume of plasma sample, required for the determination of plasma renin activity and plasma renin concentration, could be reduced to 0.6 ml and 0.05ml, respectively. A satisfactory correlation (r=0.918) was found between the plasma renin activity measured by our bioassay method reported previously and that by the present radioimmunoassay method in each of 25 different plasma samples. A highly significant correlation (r=0.968) was also observed between the plasma renin activity and the plasma renin concentration, both of which were measured by radioimmunoassays, as far as renin concentration remained under 200ng/ml/hr. On the other hand, the present results appear to indicate that, when a high plasma renin activity was obtained, it was difficult to evaluate the actual plasma renin concentration. Therefore, it would be necessary to be cautious to apply the method for plasma renin activity on the renin rich plasma.
