Mc. Paredescarbajal et al., EFFECTS OF ACUTE AND CHRONIC ESTROGENIC TREATMENT ON VASOMOTOR RESPONSES OF AORTIC RINGS FROM OVARIECTOMIZED RATS, Life sciences, 57(5), 1995, pp. 473-486
Citations number
34
Categorie Soggetti
Biology,"Medicine, Research & Experimental","Pharmacology & Pharmacy
The effects of either chronic or acute estrogenic treatment on the ''i
n vitro'' vasomotor responses to phenylephrine (10(-9)-10(-5) M) and t
o carbachol (10(-9)-10(-5) M) Of aortic rings excised from ovariectomi
zed rats were analyzed. Chronic estrogenic treatment consisted in a si
ngle subcutaneous dose of 1 mu mol estradiol 17-stearate. Effects of a
cute estrogenic treatment were evaluated by recording the responses of
aortic rings excised from untreated ovariectomized rats both before a
nd after the addition of 17 beta-estradiol to the superfusing solution
s. In order to identify the endothelium-dependent responses each exper
iment was performed simultaneously on pairs of rings from the same aor
ta, one with and the other without functional endothelium. The contrac
tile responses to phenylephrine of endothelium-intact vessels were att
enuated by chronic estrogenic treatment; this attenuation was further
increased by preincubation of the vessels with indomethacin and was re
verted by No-nitro-L-arginine methyl ester. Either chronic or acute es
trogenic treatment enhanced the carbachol-induced endothelium dependen
t relaxation of phenylephrine-precontracted rings. The results may be
explained by assuming that estrogens increase the basal release of bot
h nitric oxide and a cyclooxygenase-dependent vasoconstricting prostan
oid as well as the receptor-mediated release of nitric oxide from the
endothelium of the rat aorta.