Crocin-Induced Endothelium-Dependent Relaxation in Isolated Rat Aorta

Crocin, an active ingredient of saffron, has been found to possess hypotensive effects.
The aim of this study was to evaluate the mechanism of vasodilatory effects induced by crocin on isolated rat aorta.
To study the vasodilatory effects of crocin (0.1, 0.2, 0.4 and 0.8 M), isolated rat thoracic aorta rings were contracted by 10-6 M Phenylephrine (PE) or 80 mM of KCl. To assess the role of nitric oxide in mechanism of relaxation, induced by crocin, aortic rings were incubated by L-NG-Nitroarginine methyl ester (L-NAME: 10-6 M) for 20 minutes. Furthermore, the relaxant effect of crocin was evaluated both in intact and denuded endothelium aortic rings.
Crocin induced relaxation in endothelium-intact aortic rings precontracted with PE in a concentration dependent manner yet not in KCl precontracted aortic rings. The relaxant activity of crocin was abolished by incubation of aortic rings with L-NAME. In addition, the endothelium removal inhibited the relaxant activity of crocin.
This study indicated that relaxant activity of crocin is mainly mediated through an endothelium-dependent mechanism.