Hemeoxygenase-1 inhibits human myometrial contractility via carbon monoxide and is upregulated by progesterone during pregnancy


Nitric oxide was proposed as an endogenous inhibitor of myometrial contractility during pregnancy. Carbon monoxide (CO) like nitric oxide increases cGMP and is generated during the degradation of heme to biliverdin IX by hemeoxygenases (HO). Here we report that the expression of both HO-1 (inducible) and HO-2 (constitutive) were > 15-fold higher in pregnant myometrium compared to nonpregnant myometrium (n = 4, P <0.001, P <0.005, respectively). Moreover, the activation of the HO-CO pathway by the HO inducer, hemin (10 microM), completely inhibited spontaneous contractility (n = 3). Oxytocin-stimulated contractions (n = 5) were also significantly reduced (P <0.05) in myometrial strips mounted for isometric recording under 2 g tension in Krebs solution. Reverse transcription-PCR analysis revealed that mRNA encoding HO-1 and HO-2 was undetected in explant cultures of nonlaboring pregnant myometrium under basal conditions, however, exposure to progesterone, but not estradiol-17beta, induced the expression of HO-1 and HO-2 mRNAs. Progesterone also significantly induced HO-1 protein synthesis (n = 4, P <0.001) while estradiol-17beta had no effect (n = 4). In term (37-42-wk gestation) nonlaboring myometrial explants, CO production was stimulated by progesterone (10(-6) M) (n = 2) and hemin (10 microM) (n = 3) after 2 h of incubation and the effect of hemin was inhibited by 1 h of preincubation with the HO inhibitor tin protoporphyrin IX (20 microM). This study clearly demonstrates the expression of HO in the human myometrium and shows that its induction produces CO that limits uterine contractility in pregnant myometrium indicating a role for the HO-CO-cGMP pathway in the maintenance of the quiescent state of the uterus during pregnancy.

Publication DOI: https://doi.org/10.1172/JCI927
Divisions: College of Health & Life Sciences > Aston Medical School
College of Health & Life Sciences > School of Biosciences
College of Health & Life Sciences > School of Biosciences > Cellular and Molecular Biomedicine
College of Health & Life Sciences
Additional Information: © The American Society for Clinical Investigation, Inc.
Uncontrolled Keywords: uterus ,labor participation,carbon monoxide,smooth muscle ,progesterone
Publication ISSN: 1558-8238
Last Modified: 05 Apr 2024 07:09
Date Deposited: 20 Mar 2019 15:53
Full Text Link:
Related URLs: http://www.jci. ... ticles/view/927 (Publisher URL)
PURE Output Type: Article
Published Date: 1998-03-01
Authors: Acevedo, Carmen H.
Ahmed, Asif (ORCID Profile 0000-0002-8755-8546)



Version: Published Version

| Preview

Export / Share Citation


Additional statistics for this record