title: Involvement of atrial natriuretic peptide in blood pressure reduction induced by estradiol in spontaneously hypertensive rats.
abstract: The aim of the present study was to determine the involvement of atrial natriuretic peptide (ANP) in blood pressure (BP) alterations induced by estradiol treatment. Spontaneously hypertensive rats (SHR) and Wistar rats (WR) were ovariectomized and, after 3 weeks, were injected daily for 4 days with estradiol benzoate (E2; 5 microg/100 g/day) or a vehicle. One day after the last injection, the animals were decapitated, blood was collected, and both right and left atrial appendages were quickly removed for determination of ANP by radioimmunoassay (RIA), or used for ANP mRNA determination. Estradiol treatment induced a significant reduction of blood pressure in SHR, but not in WR. This reduction was correlated with the increase of plasma ANP levels that were significantly increased in E2-treated, compared with vehicle-treated, SHR. E2-treated SHR showed significant increases in ANP concentration in the right and left atria compared to the vehicle-treated animals. These observations were confirmed by ANP mRNA. In summary, the present study shows that short-term estradiol treatment reduces the blood pressure of ovariectomized SHR, but not of WR. This reduction was highly correlated with increased plasma estradiol and ANP levels. These results suggest that ANP is involved in mediating the effect of estradiol on blood pressure reduction.
authors.affiliation: Department of Physiology and Biophysics, Institute of Biological Science, Federal University of Minas Gerais, Av. Antonio Carlos, 6627, Belo Horizonte, MG CEP 31270-901, Brazil.
authors.forename: Najara O
authors.initials: NO
authors.lastname: Belo
authors.forename: Juliana
authors.initials: J
authors.lastname: Silva-Barra
authors.forename: Evelin C
authors.initials: EC
authors.lastname: Carnio
authors.forename: Jose
authors.initials: J
authors.lastname: Antunes-Rodrigues
authors.forename: Jolanta
authors.initials: J
authors.lastname: Gutkowska
authors.forename: Adelina M
authors.initials: AM
authors.lastname: Dos Reis
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D009320:Atrial Natriuretic Factor / Q000235:genetics / Q000502:physiology*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology*; D005260:Female; D020097:Natriuretic Peptide, Brain / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011863:Radioimmunoassay; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar
chemical_list: D000959:Antihypertensive Agents; D012333:RNA, Messenger; D020097:Natriuretic Peptide, Brain; C074283:estradiol 3-benzoate; D004958:Estradiol; D009320:Atrial Natriuretic Factor