The effect of
sesamin, a
lignan from
sesame oil, on altered
vasodilator and
vasoconstrictor responses in aortic rings from
deoxycorticosterone acetate (
DOCA)-
salt-induced hypertensive rats, were examined. The systolic blood pressure after 5-weeks
DOCA-
salt treatment was 195.0+/-2.8 mmHg, which was much higher than that of
sham-operated control animals (131.2+/-2.4 mmHg).
Sesamin feeding significantly suppressed the development of this
hypertension (167.1+/-8.6 mmHg).
Acetylcholine (ACh)-induced endothelium-dependent relaxation of aortic rings was markedly decreased in the
DOCA-
salt hypertensive animals, compared with cases of the control (pD2, 7.0+/-0.1; maximal response, 64.8+/-3.4% versus pD2, 7.7+/-0.2; maximal response, 93.3+/-2.7%). These changes were partially but significantly improved by the
sesamin feeding. This improvement seems to be related to a
nitric oxide (NO)-dependent component of ACh-induced action, because
sesamin feeding did not affect the responses to ACh in the presence of
NO synthase inhibitor. A spontaneous NO releaser (+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR 3) which exerts endothelium-independent vasodilatation, produced the same patterns of responses as those observed with ACh in cases of
DOCA-
salt treatment and
sesamin feeding.
Phenylephrine-induced vasoconstriction was enhanced by the
DOCA-
salt treatment, both in preparations with and without endothelium, but these enhancements were almost completely normalized by
sesamin feeding. Thus, dietary
sesamin could efficiently improve the abnormal
vasodilator and
vasoconstrictor responses in
DOCA-
salt hypertensive animals. These effects may contribute to the
antihypertensive activity of
sesamin.