Hy. Chan et al., Different role of endothelium/nitric oxide in 17 beta-estradiol- and progesterone-induced relaxation in rat arteries, LIFE SCI, 69(14), 2001, pp. 1609-1617
The present study was aimed to examine the different role of endothelium/ni
tric oxide in relaxation induced by two female sex hormones, 17 beta -estra
diol and progesterone in rat isolated aortas and mesenteric arteries. The i
sometric force of each ring was measured with Grass force-displacement tran
sducers in the organ bathes. 17 beta -Estradiol induced both endothelium-de
pendent and -independent relaxation in the rat aortas but only the endothel
ium-independent relaxation in the rat mesenteric arteries. In contrast, pro
gesterone induced both endothelium-dependent and -independent relaxation in
the rat mesenteric arteries but only endothelium-independent relaxation in
rat aortas. N-G-Nitro-L-arginine methyl ester and methylene blue attenuate
d the relaxant response to 17 beta -estradiol in the aortic rings or to pro
gesterone in the mesenteric arteries. Pretreatment with L-arginine antagoni
zed the effect of Nc-nitro-L-arginine methyl ester on sex hormone-induced r
elaxation. The endothelium contribution to relaxation seems to only relate
to lower concentrations of 17 beta -estradiol and progesterone. In summary,
the present results clearly demonstrate a different role of the functional
endothelium in the relaxant response to 17 beta -estradiol or progesterone
in the conduit vessel (aorta) and the resistance vessels (mesenteric arter
y). Nitric oxide contributes largely to the endothelium-dependent relaxatio
n induced by 17 beta -estradiol in the isolated aortas or by progesterone i
n the mesenteric arteries. (C) 2001 Elsevier Science Inc. All rights reserv
ed.