Referenced in: none

Automatically associated channels: Kir6.2

Title: Hypoxia-induced force increase (HIFI) is a novel mechanism underlying the strengthening of labor contractions, produced by hypoxic stresses.

Authors: Mohammed Alotaibi, Sarah Arrowsmith, Susan Wray

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 2015 Aug 4 , 112, 9763-8

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/26195731

Abstract
For successful birth, contractions need to become progressively stronger. The underlying mechanisms are unknown, however. We have found that a novel mechanism, hypoxia-induced force increase (HIFI), is switched on selectively, at term, and is essential to strengthening contractions. HIFI is initiated as contractions cyclically reduce blood flow and produce repeated hypoxic stresses, with associated metabolic and transcriptomic changes. The increases in contractility are a long-lasting, oxytocin-independent, intrinsic mechanism present only in the full-term pregnant uterus. HIFI is inhibited by adenosine receptor antagonism and blockade of cyclooxygenase-2 signaling, and partially reproduced by brief episodes of acidic (but not alkalotic) pH. HIFI explains how labor can progress despite paradoxical metabolic challenge, and provides a new mechanistic target for the 1 in 10 women suffering dysfunctional labor because of poor contractions.