In vivo dilatation of the postnatal ductus arteriosus by atrial natriuretic peptide in the rat.
BACKGROUND
Alpha-human atrial natriuretic peptide (hANP) reportedly increases in premature infants with patent ductus arteriosus (PDA).


OBJECTIVE
To clarify a possible hANP effect to reopen the postnatal ductus, we studied in vivo reopening of the postnatal DA by a recombinant hANP, carperitide, in rats.


METHODS
Near-term rat pups were incubated at 33 degrees C following caesarean section. The inner diameter of the ductus was measured with a microscope and a micrometer following rapid whole-body freezing. The DA constricted quickly after birth, and the inner diameter was 0.80 and 0.08 mm at 0 min (fetal state) and 60 min after birth. hANP concentration in the pup blood and the ductus-dilating effect of hANP were studied by subcutaneous injection of hANP at 60 min after birth, and by measurement 7, 15, 30 and 60 min later.


RESULTS
The peak hANP concentration was 790 pg/ml at 7 min with 1 mg/kg, which is similar to the level seen in preterm infants with symptomatic PDA. hANP dilated the postnatal ductus dose dependently and maximally at 7 min after injection. hANP dilated the postnatal constricted ductus completely to 0.79 mm in diameter with a large dose (10 mg/kg) and to 0.55 mm with 1 mg/kg.


CONCLUSIONS
hANP reopens the constricted postnatal DA dose dependently in rats. The increased hANP, accompanying premature PDA, may delay closure of the DA.
Toyoshima
Katsuaki
K
Section of Pediatric Cardiology, Tokyo Women's Medical University, Tokyo, Japan.
Momma
Kazuo
K
Imamura
Shinichiro
S
Nakanishi
Toshio
T
D000818:Animals; D000831:Animals, Newborn; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000494:pharmacology*; D015925:Cryopreservation; D004106:Dilatation; D004305:Dose-Response Relationship, Drug; D004373:Ductus Arteriosus / Q000187:drug effects* / Q000196:embryology / Q000473:pathology; D004374:Ductus Arteriosus, Patent / Q000473:pathology / Q000503:physiopathology; D005629:Frozen Sections; D007279:Injections, Subcutaneous; D023421:Models, Animal; D051381:Rats; D017208:Rats, Wistar; D011994:Recombinant Proteins
C472955:NPPA protein, human; D011994:Recombinant Proteins; D009320:Atrial Natriuretic Factor