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NO synthase inhibition and the uterine artery vasoconstrictor response to exercise in rabbit pregnancy
Author(s) -
O'Hagan Kathleen P,
Mangi Dana E,
Murphy Robert J
Publication year - 2008
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.22.1_supplement.957.7
Subject(s) - gestation , uterine artery , medicine , endocrinology , vasoconstriction , nitric oxide synthase , pregnancy , nitric oxide , biology , genetics
In rabbits, the uterine vasoconstrictor response to exercise is attenuated in late gestation. We asked whether this alteration in vascular control is related to enhanced production of nitric oxide (NO). Uterine artery blood flow (UtBF; Transonic) was measured in, and uterine artery conductance (UtC) was calculated for 10 rabbits during treadmill exercise (2 min at 10 m/min, 7% grade). Nonpregnant (NP) and pregnant (P) rabbits were studied on days 0 (NP) 10, 20 and 28 (term) of a 31 d gestation. Values are mean(SD). Rest UtBF [NP 2(1) to D28 17(7) ml/min] and UtC [NP 3(1) to D28 24(9) ml/min/mmHgx10 −2 ] increased progressively through gestation. Exercise reduced UtBF and UtC, although the vasoconstrictor response was attenuated during gestation (NP Δ‐50(20)% vs D28 Δ‐19(18)% P<0.01). NO synthase inhibition with nitro G ‐L‐arginine (5 mg/kg iv) reduced exercise and rest UtBF [rest NP 1(0.60); D28 15(7) ml/min) and UtC [rest NP 1.5(0.8); D28 20(11) ml/min/mmHgx10 −2 ] in NP and P rabbits. However, the % change in UtC w/exercise was unaffected by NO block regardless of gestational status: NP: Δ‐38(20)% D28; Δ‐20(23)%; P=0.2 Intact vs NO block. While NO block lowers UtBF and UtC at rest and exercise, the vasoconstrictor response is not exaggerated w/NO block either at NP or pregnancy. NO is not responsible for the gestational attenuation of uterine vasoconstriction during exercise. Supported by R15 HL77128 and MWU.