Constrictive effects of paraquat on the ductus arteriosus in fetal rats.
Rats on day 21 of pregnancy received a subcutaneous injection of paraquat (2, 7 or 25 mg/kg). The inner diameter of the ductus arteriosus (DA) of their fetuses was measured using the whole-body freezing method 1, 3, 6 and 24 hours after injection. The 7 mg/kg dose group showed a significant constriction of the DA 3 hours after paraquat treatment. The 25 mg/kg dose group showed a significant constriction 3 and 6 hours after treatment. The constrictive effect was dose-dependent, that is, the magnitude of constriction observed 3 hours after paraquat injection was greater in the 25 mg/kg dose group than in the 7 mg/kg dose group. The 2 mg/kg dose group showed no significant change in the inner diameter of the DA at any point of measurement (1, 3, 6 and 24 hours after injection), compared to the saline treated controls. These results indicate that paraquat induces constriction of the fetal rat DA in a dose-dependent manner when administered in late stages of gestation, and that this effect of paraquat is not seen at a dose level of 2 mg/kg.
Department of Veterinary Pharmacology, School of Veterinary Medicine, Azabu University, Kanagawa, Japan.
T
T
Masaoka
M
M
Shirai
H
H
Takagi
M
M
Yamamoto
K
K
Arishima
F
F
Akahori
D000818:Animals; D004305:Dose-Response Relationship, Drug; D004373:Ductus Arteriosus / Q000187:drug effects*; D005260:Female; D005865:Gestational Age; D008431:Maternal-Fetal Exchange / Q000502:physiology; D010269:Paraquat / Q000008:administration & dosage / Q000633:toxicity*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D014661:Vasoconstriction / Q000187:drug effects
D010269:Paraquat