Effects of estrogens and selective estrogen receptor modulators on vascular reactivity in the perfused mesenteric vascular bed.
Estrogens and selective estrogen receptor modulators (SERMs), such as raloxifene (RAL) and tamoxifen (TAM), acutely relax arteries, but the long-term effects of estrogens and SERMs on vascular reactivity in the mesenteric vasculature have not been well defined. In this study, we used an isolated, perfused mesenteric vascular bed technique to investigate the effect of chronic treatment of estrogens and SERMs on vascular reactivity of the mesenteric bed. Ovariectomized female Sprague-Dawley rats were treated by gavage with vehicle (control, 2-hydroxypropyl-beta-cyclodextrin), ethinyl estradiol, estradiol benzoate, equilin (EQ), TAM, or RAL for 3 wk. EQ and TAM increased vasoconstriction in response to all three vasoconstrictors tested (KCl, norepinephrine, and 5-HT). Ethinyl estradiol increased vasoconstriction in response to KCl and 5-HT, whereas responses to estradiol benzoate and RAL were less consistent. Only EQ (134 +/- 4 mmHg) and TAM (104 +/- 4 mmHg) changed mean arterial blood pressure compared with control (117 +/- 4 mmHg). These data demonstrate that 3-wk gavage treatment with estrogens and SERMs affects vascular reactivity in the mesenteric vascular bed. However, the three formulations of estrogen did not produce equivalent effects, and the effects of the SERMs were different from those of the estrogens.
Mark
Connie J
CJ
Division of Basic Biomedical Sciences, Sanford School of Medicine, University of South Dakota, Vermillion, SD 57069, USA.
Tatchum-Talom
Rabelais
R
Martin
Douglas S
DS
Eyster
Kathleen M
KM
D000818:Animals; D001835:Body Weight / Q000187:drug effects / Q000502:physiology; D002626:Chemistry, Pharmaceutical; D003627:Data Interpretation, Statistical; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology*; D005260:Female; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000494:pharmacology; D010052:Ovariectomy; D010477:Perfusion; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats; D020845:Selective Estrogen Receptor Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D012701:Serotonin / Q000494:pharmacology; D013152:Splanchnic Circulation / Q000187:drug effects*; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004967:Estrogens; D020845:Selective Estrogen Receptor Modulators; D014662:Vasoconstrictor Agents; D012701:Serotonin; D011189:Potassium Chloride; D009638:Norepinephrine