We tested the hypothesis that oxytocin-induced labor augmented IL-1β-induced/-stimulated lung fluid absorption in preterm guinea pig fetuses. IL-1β 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-1β. Labor induction by oxytocin augmented IL-1β-induced/- stimulated lung fluid absorption. Metyrapone pretreatment did not affect oxytocin-induced/-stimulated lung fluid absorption, while completely blocking IL-1β-induced/-stimulated fluid absorption. Fetal lung fluid absorption, when present, was always propranolol and amiloride sensitive, suggesting that β-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-1β, but not further by oxytocin. Our results indicate that IL-1β release into the maternal blood circulation positively affects lung maturation due to the IL-1β-induced release of cortisol and thus prepares the lungs for the epinephrine surge associated with labor.
| Identifer | oai:union.ndltd.org:ETSU/oai:dc.etsu.edu:etsu-works-19595 |
| Date | 01 December 2005 |
| Creators | Nair, Prem K., Li, Tianbo, Bhattacharjee, Reshma, Ye, Xin, Folkesson, Hans G. |
| Publisher | Digital Commons @ East Tennessee State University |
| Source Sets | East Tennessee State University |
| Detected Language | English |
| Type | text |
| Source | ETSU Faculty Works |
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