title: Noninvasive assessment of coronary microcirculatory function in postmenopausal women and effects of short-term and long-term estrogen administration.
abstract: BACKGROUND
  Estrogen improves endothelial function in the coronary conduit vessels of animals; however, its effects on the coronary microcirculation have not been studied completely in humans.
  
  
  RESULTS
  We measured myocardial blood flow (MBF) with a PET scan at rest, during cold pressor testing (CPT), and during dipyridamole hyperemia in 54 postmenopausal women without coronary artery disease. Of these, 23 were not and 31 women were taking long-term hormone replacement therapy (HRT) using estrogen either alone or with a progestogen. Each group was subdivided by coronary risk factors (RFs). Twelve young healthy women served as controls. In women not taking HRT, MBF measurements were repeated after 25 mg of conjugated equine estrogens IV. Neither short estrogen nor long-term HRT affected MBF at rest in women with and without RFs. Dipyridamole MBF was attenuated only in the women with RF who were not taking HRT. Short-term estrogen and long-term HRT did not reverse the abnormal response. MBF responses to CPT were abnormal in women not taking HRT, regardless of RFs (20+/-15% versus 32+/-21%) and remained unchanged after short-term estrogen administration. Long-term HRT normalized the response to CPT only in women without RF (53+/-22% versus 59+/-36% in the young women; NS). MBFs were similar for women on estrogen alone or estrogen plus a progestogen, regardless of presence or absence of RFs.
  
  
  CONCLUSIONS
  Menopause is associated with abnormal CPT (an indirect measure of endothelial function), which can be reversed by long-term HRT only when RFs are absent. Progestogens do not antagonize this effect. Long-term HRT may therefore be useful in the primary prevention of coronary artery disease in women without RFs.
authors.affiliation: Department of Molecular and Medical Pharmacology, UCLA School of Medicine, Los Angeles, CA 90095-1735, USA.
authors.forename: Roxana
authors.initials: R
authors.lastname: Campisi
authors.forename: Lauren
authors.initials: L
authors.lastname: Nathan
authors.forename: Miguel Hernandez
authors.initials: MH
authors.lastname: Pampaloni
authors.forename: Heiko
authors.initials: H
authors.lastname: Schöder
authors.forename: James W
authors.initials: JW
authors.lastname: Sayre
authors.forename: Gautam
authors.initials: G
authors.lastname: Chaudhuri
authors.forename: Heinrich R
authors.initials: HR
authors.lastname: Schelbert
mesh_terms: D000328:Adult; D003080:Cold Temperature; D003326:Coronary Circulation / Q000187:drug effects / Q000502:physiology*; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000187:drug effects; D004176:Dipyridamole; D015914:Estrogen Replacement Therapy; D004966:Estrogens, Conjugated (USP) / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D006940:Hyperemia / Q000139:chemically induced; D008833:Microcirculation / Q000000981:diagnostic imaging / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D017698:Postmenopause / Q000097:blood* / Q000187:drug effects / Q000502:physiology; D011312:Pressure; D013997:Time Factors; D014055:Tomography, Emission-Computed; D014665:Vasodilator Agents
chemical_list: D004966:Estrogens, Conjugated (USP); D014665:Vasodilator Agents; D004176:Dipyridamole