title: Oxytocin-induced labor augments IL-1beta-stimulated lung fluid absorption in fetal guinea pig lungs.
abstract: We tested the hypothesis that oxytocin-induced labor augmented IL-1beta-induced/-stimulated lung fluid absorption in preterm guinea pig fetuses. IL-1beta was administered subcutaneously daily to timed-pregnant guinea pigs for 3 days with and without simultaneous cortisol synthesis inhibition by metyrapone. At day 3, oxytocin was administered, and fetuses were delivered by abdominal hysterotomy at 61 and by oxytocin-induced birth at 68 days gestation. Delivered fetuses were instilled with isosmolar 5% albumin into the lungs, and lung fluid movement was measured over 1 h by mass balance. Lung fluid absorption was induced in 61-day and stimulated in 68-day gestation lungs by IL-1beta. Labor induction by oxytocin augmented IL-1beta-induced/-stimulated lung fluid absorption. Metyrapone pretreatment did not affect oxytocin-induced/-stimulated lung fluid absorption, while completely blocking IL-1beta-induced/-stimulated fluid absorption. Fetal lung fluid absorption, when present, was always propranolol and amiloride sensitive, suggesting that beta-adrenoceptor stimulation and amiloride-sensitive sodium channels were critical for fluid absorption. Epithelial sodium channel and Na-K-ATPase subunit expressions were both increased by IL-1beta, but not further by oxytocin. Our results indicate that IL-1beta release into the maternal blood circulation positively affects lung maturation due to the IL-1beta-induced release of cortisol and thus prepares the lungs for the epinephrine surge associated with labor.
authors.affiliation: Dept. of Physiology and Pharmacology, College of Medicine, Northeastern Ohio University, 4209 State Rte. 44, PO Box 95, Rootstown, OH 44272-0095, USA.
authors.forename: Prem K
authors.initials: PK
authors.lastname: Nair
authors.forename: Tianbo
authors.initials: T
authors.lastname: Li
authors.forename: Reshma
authors.initials: R
authors.lastname: Bhattacharjee
authors.forename: Xin
authors.initials: X
authors.lastname: Ye
authors.forename: Hans G
authors.initials: HG
authors.lastname: Folkesson
mesh_terms: D000042:Absorption / Q000187:drug effects; D000584:Amiloride / Q000008:administration & dosage; D000818:Animals; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D004837:Epinephrine / Q000378:metabolism; D015633:Extravascular Lung Water / Q000378:metabolism*; D005260:Female; D005325:Fetal Organ Maturity / Q000187:drug effects; D005333:Fetus / Q000378:metabolism; D006168:Guinea Pigs; D006854:Hydrocortisone / Q000378:metabolism; D007375:Interleukin-1 / Q000008:administration & dosage* / Q000378:metabolism; D017136:Ion Transport / Q000187:drug effects; D007751:Labor, Induced; D008168:Lung / Q000196:embryology*; D008431:Maternal-Fetal Exchange / Q000187:drug effects; D008797:Metyrapone / Q000008:administration & dosage; D010120:Oxytocics / Q000008:administration & dosage*; D010121:Oxytocin / Q000008:administration & dosage*; D011247:Pregnancy; D011433:Propranolol / Q000008:administration & dosage; D026941:Sodium Channel Blockers / Q000008:administration & dosage; D028021:Sodium-Potassium-Chloride Symporters / Q000378:metabolism; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D004791:Enzyme Inhibitors; D007375:Interleukin-1; D010120:Oxytocics; D026941:Sodium Channel Blockers; D028021:Sodium-Potassium-Chloride Symporters; D014665:Vasodilator Agents; D010121:Oxytocin; D000584:Amiloride; D011433:Propranolol; D006854:Hydrocortisone; D004837:Epinephrine; D008797:Metyrapone