Effects of sesamin on altered vascular reactivity in aortic rings of deoxycorticosterone acetate-salt-induced hypertensive rat

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 (pD(2), 7.0+/-0.1; maximal response, 64.8+/-3.4% versus pD(2), 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.