Studies of the immaturity of the ADH-dependent cAMP system in conscious newborn piglets--possible impairing effects of renal prostaglandins.

In 24 conscious newborn piglets the effects of 20 micrograms/kg body weight IV 1-deamino-8-D-arginine-vasopressin (DDAVP) in group 1, 5 mg/kg PO indomethacin in group 2, and the combined effects of both drugs in group 3 were studied by measuring urinary flow rate, urinary osmolality, creatinine clearance, total urinary and nephrogenous cyclic-adenosine 3':5'-monophosphate (cAMP) excretion, medullary cAMP content, and renal prostaglandin (PG)E2 and PGF2 alpha, excretion. DDAVP alone had no significant effects on ther above parameters, whereas indomethacin alone reduced only the PG excretion significantly. When both drugs were administered simultaneously, urinary concentration increased significantly (urinary flow rate decreased from 2.4 +/- 0.4 to 1.4 +/- 0.3 ml/hr (means +/- S.E.), and urinary osmolality increased from 444 +/- 29 to 552 +/- 33 mOsm/liter). Total urinary and nephrogenous cAMP excretion increased from 590 +/- 48 to 854 +/- 78 and 302 +/- 36 to 590 +/- 81 pmoles/hr/g kidney weight, respectively, whereas PGE2 and PGF2 alpha decreased from 249 +/- 33 to 19 +/- 4 and 192 +/- 32 to 43 +/- 7 pg/hr/g kidney weight, respectively. In addition, medullary cAMP content was considerably higher in group 3 (2010 +/- 200 pmoles/g medulla) than that observed in the control (1187 +/- 137), DDAVP (1218 +/- 115), and indomethacin (1230 +/- 168) groups.