Newborn cardiorenal dynamics: a state of atrial natriuretic peptide unresponsiveness.
The newborn has an attenuated response to saline fluid challenge. We studied the response of endogenous atrial natriuretic peptides (ANF) to 10% body weight graded isotonic saline volume expansion (VE) in 14 anesthetized neonatal lambs which were either 1 day old or 7 days old. Plasma ANF values were unchanged at 3.3% and 10% VE compared with control values (56 +/- 28 vs. 66 +/- 17 and 66 +/- 37 pg/ml, not significant) in the 1-day-old lambs, whereas values increased significantly at both 3.3% and 10% VE (47 +/- 40 vs. 99 +/- 57 and 96 +/- 73, P = 0.022 and P = 0.018, respectively) in the 7-day-old lambs. No relationship existed between right atrial (RAP) or pulmonary capillary wedge pressures (PCWP) and plasma ANF in the 1-day-old lambs; however, a significant correlation existed (RAP, P = 0.015; PCWP, P = 0.022) in the 7-day-old lambs. In general, renal function was improved in the 7-day-old lambs compared with the 1-day-old lambs, but only changes in fractional sodium excretion were significantly different (P = 0.017). We speculate that ANF unresponsiveness in the 1-day-old lamb is related to physiological transitions during the birth process and that the maturation of the renal response to VE may require maturation of the atrial mechanism which permits ANF secretion.
Silberbach
M
M
Division of Pediatric Cardiology, University of Minnesota, Minneapolis 55405.
Stejskal
E
E
Foker
J
J
Bianco
R
R
Tobian
L
L
Burnett
J C
JC
Einzig
S
S
D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D016280:Atrial Function, Right / Q000502:physiology; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000494:pharmacology*; D006321:Heart / Q000254:growth & development / Q000502:physiology*; D006439:Hemodynamics; D007668:Kidney / Q000098:blood supply / Q000254:growth & development / Q000502:physiology*; D010953:Plasma Volume; D011312:Pressure; D011669:Pulmonary Wedge Pressure; D012756:Sheep
D009320:Atrial Natriuretic Factor