Atrial natriuretic peptide, cyclic guanosine monophosphate and sodium excretion during postnatal adaptation in male infants below 34 weeks gestation with severe respiratory distress syndrome.
The role of atrial natriuretic peptide (ANP), in the perinatal period, is at present unclear. In adults urinary cyclic guanosine monophosphate (cGMP) is considered an index of the biological activity of plasma ANP. The aim of this study was to determine the relationship between plasma ANP, cGMP excretion (cGMPex) and sodium excretion (Naex) in preterm infants in the first days after birth. Sequential, 4 hourly, measurements of plasma ANP, cGMPex and Naex were made in 12 male neonates of median gestational age 27 weeks (range 25-33) and median birth weight 0.981 kg (range 0.635-2.029) over a median period of 5.2 days (range 2.3-10). The ratios of cGMPex to ANP and of Naex to cGMPex were each plotted against postnatal age. The ratio of cGMPex to ANP increased ten fold in the first 3-4 days after birth but then remained relatively constant; the ratio of Naex to cGMPex showed a steady increase from birth. We conclude that, in extremely immature infants, renal sodium loss in response to cGMP increases rapidly during the first 10 days after birth. In addition, after 3-4 days from birth, plasma ANP ia associated with a constant proportionate rate of cGMP excretion though, as the plateau ratio of cGMPex to ANP varied widely between babies, cGMPex cannot be used to predict plasma ANP in cross sectional studies. These changes may reflect postnatal adaptation and/or maturation of both ANP receptors and cGMP mediated cascades. In the immediate postnatal period, plasma ANP may also have a non-renal role.
Midgley
J
J
Department of Paediatrics, Royal Postgraduate Medical School, Queen Charlotte's and Chelsea Hospital, London, U.K.
Modi
N
N
Littleton
P
P
Carter
N
N
Royston
P
P
Smith
A
A
D000367:Age Factors; D009320:Atrial Natriuretic Factor / Q000097:blood*; D006152:Cyclic GMP / Q000652:urine*; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D012127:Respiratory Distress Syndrome, Newborn / Q000378:metabolism*; D012964:Sodium / Q000652:urine*
D009320:Atrial Natriuretic Factor; D012964:Sodium; D006152:Cyclic GMP