The effect of vitamin A on contraction of the ductus arteriosus in fetal rat.
Endogenous retinoic acid may play a role in inducing smooth muscle differentiation in the fetal ductus arteriosus. Maternal administration of retinoic acid may accelerate the process. This study was designed to investigate the effect of vitamin A on developmental changes in the contractile system of the ductus. Vitamin A was injected into pregnant rats and the ductus was isolated from the fetus at 19, 20, or 21 d of gestation. The fetus at 19 d of gestation served as a model of the preterm fetus. The force of contraction and [Ca]i were measured. Membrane depolarization caused by high KCl induced ductal contraction in all age groups studied. In the 19-d fetus, O2 did not cause significant contraction or changes in [Ca]i in the control group, but it did induce a significant contraction and increases in [Ca]i in the vitamin A-treated group. In the 20- and 21-d fetuses, 5% O2-induced contraction in the vitamin A-treated group was significantly greater than in the control group. In the 19-d fetus, noradrenaline-induced contraction and increases in [Ca]i, indicators of the size of the intracellular Ca pool, were observed and they were similar in the control group and in the vitamin A-treated group. These data suggest that 1) in the preterm fetus, the contractile system, including membrane depolarization, [Ca]i increase, and its activation of contractile proteins, is already functioning, but the O2-sensing mechanism is underdeveloped, 2) vitamin A accelerates the development of the O2-sensing mechanism of the ductus arteriosus.
Wu
G R
GR
Department of Pediatric Cardiology, The Heart Institute of Japan, Tokyo Women's Medical University, Tokyo, 162 Japan.
Jing
S
S
Momma
K
K
Nakanishi
T
T
D000818:Animals; D002118:Calcium / Q000378:metabolism; D004373:Ductus Arteriosus / Q000187:drug effects* / Q000196:embryology / Q000502:physiology; D004730:Endothelium, Vascular / Q000502:physiology; D005260:Female; D005333:Fetus / Q000187:drug effects; D007213:Indomethacin / Q000494:pharmacology; D008431:Maternal-Fetal Exchange; D009119:Muscle Contraction / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D010100:Oxygen / Q000008:administration & dosage; D011189:Potassium Chloride / Q000494:pharmacology; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects; D014801:Vitamin A / Q000494:pharmacology*
D014801:Vitamin A; D011189:Potassium Chloride; D010100:Oxygen; D002118:Calcium; D009638:Norepinephrine; D007213:Indomethacin