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Role of sex steroids in the regulation of the UA myogenic tone during pregnancy at high‐altitude
Author(s) -
Chang Katherine,
Xiao Daliao,
Xue Qin,
Zhang Lubo
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.575.5
Subject(s) - endocrinology , medicine , hypoxia (environmental) , pregnancy , hormone , receptor , uterine artery , effects of high altitude on humans , biology , chemistry , gestation , oxygen , anatomy , genetics , organic chemistry
Previous studies demonstrated that sex steroids mediate a reduction in myogenic tone of the uterine artery (UA) during pregnancy. The present study tested whether chronic hypoxia (CH) alters hormonal effects on the UA. UAs were isolated from nonpregnant and near‐term pregnant (PUA) ewes maintained at ~300 m or 3801 m altitude for 110 days. UAs were treated with 17b‐estradiol (E2b), progesterone (P4), hormone inhibitors for 48 h. In contrast to previous findings in the normoxic animals, E2b and P4 had no effect on the myogenic tone and PKC‐induced contractions in the UA of high‐altitude animals. Additionally, high altitude hypoxia decreased ERá expression in PUA whereas ERb and progesterone receptor expression was unaltered. To determine the direct effect of hypoxia, UAs of normoxic animals were incubated in 10.5% or 21% oxygen for 48h, and our results showed that ERá expression in PUA was lowered in the 10.5% group than in the 21% group. The results suggest that CH differentially regulates the expression of steroid receptors in the UAs, leading to increased myogenic tone and impaired uterine blood flow during pregnancy.(supported in part by NIH grant HL89012)