THE RENIN-ANGIOTENS IN-ALDOSTERONE SYSTEM IN HEALTHY INFANTS AND CHILDREN

Abstract

Previous investigations have shown that, in healthy children, active renin values, measured as plasma renin activity (PRAact), and plasma aldosterone (PA) values are increased when compared to adult values. No correlation between PRA and PA was observed. Inactive renin values (PRAinact) obtained after cryoactivation did not decrease with age. Moreover, in some children, mainly infants, PRA decreased after cold treatment. In the present investigation it was shown that, in healthy children, active renin values, measured as plasma renin concentration (PRC), are also increased. There was a significant correlation with angiotensin II (AII) values. No correlation, however was found between AII and PA values, confirming the earlier suggestion that other factors than the RAA-system are involved in the high aldosterone secretion. Although the mean activation rate of inactive renin was higher with cold than with acid treatment, the difference between both methods was not obvious in individual cases. After addition of o.phenanthrolin to the blood samples, no negative values for PRAinact were observed. It is suggested that the previous negative values were due to insufficient inactivation of the Ca- and Zn-dependent enzymes involved in the system.