MEASUREMENT OF ATRIAL NATRIURETIC PEPTIDE (ANP), cGMP, ALDOSTERONE AND VASOPRESSIN LEVELS IN INFANTS

In our first studies we found elevated plasma levels of ANP and its second messenger cGMP in newborns and in children with cardiac diseases. Despite these high levels there is no effect on the water and electrolyte excretion. The lacking response to ANP in these patients may be explained by an enhanced release of other volume regulating hormones. To prove this hypothesis we measured plasma and urinary levels of ANP and cGMP as well as urinary excretion of aldosterone (Aldo) and vasopressin (AVP) in 22 healthy infants and 26 infants with cardiac diseases. Urine was collected for 8 hours from 10 p.m. to 6 a.m. In children with cardiac diseases we found significantly higher plasma levels of ANP ( = 225 ± 65 pg/ml) and cGMP ( = 8,5 ± 4,5 pmol/ml) and urinary levels of cGMP ( = 30 ± 5 nmol/8h/kg), Aldo ( = 800 ± 20 pg/8h/kg)and AVP (1100 ± 250 pg/8h/kg) than in control infants (p < 0.001). There was no correlation between ANP or cGMP levels and water- and sodiumexcretion.