The vascular dilatation induced by Hydroxysafflor yellow A (HSYA) on rat mesenteric artery through TRPV4-dependent calcium influx in endothelial cells.

Hydroxysafflor yellow A (HSYA) is the principal constituent of the flowers of Carthamus tinctorius L., a traditional Chinese herbal medicine, which has been used for the treatment of cerebrovascular and cardiovascular diseases due to its property of promoting blood circulation and removing blood stasis. It is dominated in the water extract of Carthamus tinctorius L., which has been used in the clinical treatment for cardiovascular diseases. HSYA exerts a variety of pharmacological efficacy upon the vascular system. However, the underlying mechanisms remain unclear. To investigate the vascular dilatation effect of HSYA on rat mesenteric artery (MA) and its potential mechanism. Adult male Wistar rats were applied to the study. Tension studies were conducted to determine the dilatation activity of HSYA against pre-contracted mesenteric arterial (MA) rings by U 46619 and Phenylephrine (PE). The vascular activities were measured with or without incubation with some selective inhibitors, including L-N(ω)-nitro-L-arginine methyl ester (L-NAME, a nitro oxide synthase inhibitor), HC-067047 (a selective TRPV4 antagonist), BaCl2 (a Kir channel blocker), and Indomethacin (Indo, a nonselective cyclooxygenase inhibitor), respectively. Immunocytochemistry, Calcium Imaging, NO Production detection, and Western Blot were also employed to further study the underlying mechanism. HSYA reversed the constriction of MAs induced by U 46619 in a manner of concentration dependency, and the dilatation capability was reversed by L-NAME. This effect was significantly dependent on the intactness of MA endothelium, accompanying an increment of NO production in mesenteric arterial endothelium cells. The increment of NO production was reversed by inhibiting the PKA. Also, the expression of p-eNOS was activated by HSYA shown in Western Blot assays. The cells imaging revealed a significant increase and drop of the influx of Ca2+ before and after treatment with HC-067047. These findings suggest that HSYA exerts vessel dilation effect on MAs via a TRPV4-dependent influx of Ca2+ in endothelium cells, PKA-dependent eNOS phosphorylation and NO production mechanism. The present study indicates that HSYA has the potential to be a future candidate for the treatment of hypertension.

Yang J ，Wang R ，Cheng X ，Qu H ，Qi J ，Li D ，Xing Y ，Bai Y ，Zheng X ... -  《-》

Hydroxysafflor yellow A (HSYA) attenuates hypoxic pulmonary arterial remodelling and reverses right ventricular hypertrophy in rats.

Carthamus tinctorius L. is a traditional herbal medicine native to China with properties of promoting blood circulation and removing blood stasis, which is used for the treatment of cerebrovascular and cardiovascular diseases. Hydroxysafflor yellow A (HSYA) is the main constituent isolated from the flower of Carthamus tinctorius L. which is used as a marker substance in the quality control of Carthamus tinctorius L. in Chinese Pharmacopeia. This study is to investigate the hypertension attenuating effect of HSYA on hypoxia-induced pulmonary artery hypertension model rats, and the possible mechanism. The animal models were made by treating adult male Wistar rats (of the same age with the same weight of 200±25g) under hypoxia 24h per day for 9 days with or without administration of HSYA. The pulmonary arterial pressure of rats was measured after anesthetization; The right ventricular hypotrophy was evaluated by the right ventricular hypotrophy index (RVHI=[RV/(LV+S)]) as well as histomorphology assay with Hematoxylin and Eosin (HE) staining; The reducing of pulmonary artery remodelling was evaluated by histomorphology assay with HE staining; The proliferation of pulmonary artery smooth muscle cells (PASMCs) was evaluated by immunohistochemistry assays (PCNA and Ki67) and MTT assay. Cell cycle analysis and Weston-blot analysis were also performed in the study. HSYA reduced the mean right ventricular systolic pressure (RVSP) of rats with hypoxic pulmonary arterial hypertension (HPH) in a manner of concentration dependency. It significantly inhibited the PASMCs proliferation and attenuated the remodelling of the pulmonary artery and right ventricular hypertrophy. These findings suggested that HSYA protected against hypoxic induced pulmonary hypertension by reversing the remodelling of the pulmonary artery through inhibiting the proliferation and hypertrophy of PASMCs. This is in accordance with our previous finding that HSYA protects against the pulmonary artery vascular constriction. All these results suggest that HSYA may be a promising candidate for HPH treatment.

Li L ，Dong P ，Hou C ，Cao F ，Sun S ，He F ，Song Y ，Li S ，Bai Y ，Zhu D ... -  《-》

Hydroxysafflor yellow A (HSYA) from flowers of Carthamus tinctorius L. and its vasodilatation effects on pulmonary artery.

Bai Y ，Lu P ，Han C ，Yu C ，Chen M ，He F ，Yi D ，Wu L ... -  《MOLECULES》

Morin induces endothelium-dependent relaxation by activating TRPV4 channels in rat mesenteric arteries.

Morin, a natural flavonol, has been reported to have beneficial pharmacological effects. Although its vascular protective effects have been studied, little is known about its effects on the mesenteric artery and the underlying mechanisms. Transient receptor potential vanilloid type 4 (TRPV4) channels are one of the most important Ca2+-permeable cation channels in vascular endothelial cells and play an important role in regulating rat mesenteric vascular tone. In the present study, the myogenic effects of morin were investigated using wire and pressure myography in the isolated mesenteric artery. Morin induced endothelium-dependent relaxation of isolated rat mesenteric arteries in a concentration-dependent manner. In addition, morin stimulated relaxation by activating TRPV4-mediated Ca2+ influx without affecting the nitric oxide (NO), hydrogen peroxide (H2O2), cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) pathways. In primary cultured rat mesenteric artery endothelial cells and over-expressing TRPV4 HEK 293 cells, the TRPV4 inhibitor HC067047 significantly reduced the morin-induced increase in intracellular Ca2+ concentration. Furthermore, in rats with hypertension induced by NꞶ-nitro-L-arginine methyl ester (L-NAME), oral administration of morin (50 mg/kg/day) decreased systolic blood pressure. In L-NAME-induced hypertensive rats, morin significantly improved the relaxation response of the arteries to acetylcholine. Thus, we demonstrated that morin induces endothelium-dependent relaxation in the rat mesenteric artery by acting on TRPV4 channels to mediate Ca2+ influx and attenuate blood pressure in L-NAME-induced hypertension, thereby highlighting the potential of morin in the treatment of hypertension.

Zhang X ，Mao A ，Xiao W ，Zhang P ，Han X ，Zhou T ，Chen Y ，Jin J ，Ma X ... -  《-》

Hydroxysafflor yellow A actives BK(Ca) channels and inhibits L-type Ca channels to induce vascular relaxation.

Hydroxy-safflor yellow A (HSYA) can exert a variety of effects upon the vascular system. However, the underlying mechanisms are not clear. The present study is to investigate its vasodilating effect and the mechanisms. Wistar-Kyoto (WKY) rats and spontaneously hypertensive rats (SHR) were enrolled for studying effects of HSYA on blood pressure, vasodilation, intracellular Ca2+ transient and membrane ion channels. Vasodilation and intracellular Ca2+ transient were measured by using vasomotor assay and fluorescence imaging system, respectively. The effect of HSYA on the large conductance Ca2+ activated and voltage-gated potassium channel (BKCa channel) currents in rat mesentery artery and on L-type calcium channel (Ca-L) currents in HEK293cells expressed with Ca-L were investigated using patch clamp techniques. Blood pressure of SHR and WKY rats were concentration dependently reduced by HSYA with a larger effect of HSYA in SHR than that in WKY rats. The tension of mesenteric arteries induced by 3 μM phenylephrine was attenuated by HSYA (IC50 = 90.8 μΜ). Patch clamp study showed that HSYA could activate BKCa channels and suppress Ca-L channels in a concentration dependent manner. The results of calcium signaling assays indicated that HSYA could reduce the intracellular free Ca2+ level. These findings demonstrate that HSYA could activate BKCa channels and inhibit Ca-L channels and reduce intracellular free Ca2+ level, which are probably important for its vasodilatory effect.

Wang N ，He D ，Zhou Y ，Wen J ，Liu X ，Li P ，Yang Y ，Cheng J ... -  《-》