title: The effect of isosorbide dinitrate on uterine and ovarian blood flow in cycling and early pregnant mares: A pilot study.
abstract: Poor uterine perfusion has been proposed as a cause of infertility in mares. The objective of this study was to investigate the effect of isosorbide dinitrate (ISDN), a nitric oxide donor, on uterine and ovarian blood flow resistance during diestrus and early pregnancy in mares. Six Trotter mares, aged 7 to 14 years, were examined daily during the first 11 days of three diestrous periods, and five of those mares were also examined during the first 11 days of two pregnancies. Six mares randomly received a placebo, a low dose (30 mg, ISDN30), or a high dose of ISDN (60 mg, ISDN60) through three nonconsecutive cycles. The treatments were administered orally, every 12 hours from Day 1 to 11 of the cycle (Day 0 = ovulation). Five of the 6 mares received a placebo or 60 mg of ISDN orally every 12 hours from Day 1 to 11 of pregnancy. The mares were short cycled on Day 12 of each trial. Transrectal color Doppler was used to determine blood flow resistance semiquantitatively and expressed as pulsatility index. Mean pulsatility index of both uterine arteries combined and of the dominant (ipsilateral to the CL) ovarian artery was lower (treatment effects: P ≤ 0.01; time effects: P ≤ 0.002) in mares receiving 30 mg or 60 mg of ISDN compared with placebo-treated mares. Blood flow resistance in the dominant ovarian artery was lower in ISDN-treated pregnant mares than in placebo-treated pregnant and cycling mares (treatment effect: P = 0.04; time effect: P = 0.003). Isosorbide dinitrate increases uterine and ovarian perfusion in cycling mares and ovarian perfusion in early pregnant mares. Further studies are needed to investigate these effects in relation to fertility of the mare.
authors.affiliation: Vetsuisse Faculty, Clinic of Reproductive Medicine, University of Zurich, Zurich, Switzerland. Electronic address: dzoller@vetclinics.uzh.ch.
authors.forename: D
authors.initials: D
authors.lastname: Zoller
authors.affiliation: Vetsuisse Faculty, Clinic of Reproductive Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Lüttgenau
authors.affiliation: Vetsuisse Faculty, Clinic of Reproductive Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Steffen
authors.affiliation: Vetsuisse Faculty, Clinic of Reproductive Medicine, University of Zurich, Zurich, Switzerland.
authors.forename: H
authors.initials: H
authors.lastname: Bollwein
mesh_terms: D000818:Animals; D001783:Blood Flow Velocity / Q000187:drug effects*; D005260:Female; D006439:Hemodynamics; D006736:Horses / Q000502:physiology*; D007548:Isosorbide Dinitrate / Q000008:administration & dosage / Q000627:therapeutic use*; D010053:Ovary / Q000098:blood supply / Q000187:drug effects*; D010865:Pilot Projects; D011247:Pregnancy; D014599:Uterus / Q000098:blood supply / Q000187:drug effects*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use*
chemical_list: D014665:Vasodilator Agents; D007548:Isosorbide Dinitrate
keywords: Early pregnancy; Equine; Estrous cycle; Genital blood flow; Nitric oxide