Vasorelaxant effects of Cerebralcare Granule® are mediated by NO/cGMP pathway, potassium channel opening and calcium channel blockade in isolated rat thoracic aorta.

Cerebralcare Granule (CG), one of the famous classical recipes in traditional Chinese medicine, is developed from the "Decoction of Four Drugs". It has been used for treatment of cerebrovascular related diseases, such as hypertension. It is well known that vasodilatation plays a very important role in hypertensive. Despite the popular medicinal use of CG, little data was available to its activity and mechanism involved in vasodilatation. Therefore, we aimed to investigate the vasorelaxant effects of CG on isolated rat thoracic aorta so as to assess some of the possible mechanisms. The present study was performed to examine the vasodilative activity of CG and its mechanisms in isolated rat thoracic aorta. CG was studied on isolated rat thoracic aorta in vitro, including endothelium-intact and endothelium-denuded aortic rings. In present study, specific inhibitors including NO synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME), cyclooxygenase (COX) inhibitor indomethacin (INDO), non-selective K+ channel inhibitor tetraethylammonium chloride (TEA), Kir channel inhibitor BaCl2, KATP channel inhibitor Glibenclamide (Gli) and cholinergic receptor antagonist atropine were used, they were added 20 min before NE contraction and then added CG-induced vasodilation. Removal of endothelium or pretreatment of aortic rings (intact endothelium) with L-NAME (0.1 mM) or INDO (0.01 mM) significantly blocked the CG induced relaxation. Pretreatment with the non-selective K+ channel inhibitor TEA (1 mM), or the Kir channel inhibitor BaCl2 (0.1 mM), neither of them had no influence on the CG-induced response (p>0.05). However, pretreatment with the KATP channel inhibitor Gli (0.01 mM) produced significant inhibition on the CG-induced response (p<0.01). Besides, CG also inhibited the contraction triggered by NE in endothelium-denuded rings in Ca2+-free medium. CG (0.4, 0.8 and 3.2 mg/mL) produced rightward parallel displacement of CaCl2 curves and reduced the maximum contraction induced by 30 mM CaCl2 to 31.1±9.3%, 18.8±6.9% and 9.4±4.5%, respectively. The relaxation, induced by CG on endothelium-intact rat aortic rings pre-contracted with NE, was significantly attenuated in the presence of atropine (EC50=3.7 mg/mL, p<0.01). Our results suggest that CG induces relaxation in rat aortic rings through an endothelium-dependent pathway mediated by NO/cGMP pathway and an endothelium-independent pathway involving blockade of Ca2+ channels, inhibition of Ca2+ mobilization from intracellular stores, opening of KATP channel. In addition, the muscarinic receptor stimulation is also one of the vasorelaxant mechanisms.

Qu Z ，Zhang J ，Gao W ，Chen H ，Guo H ，Wang T ，Li H ，Liu C ... -  《-》

Vasorelaxant effects of Shunaoxin pill are mediated by NO/cGMP pathway, HO/CO pathway and calcium channel blockade in isolated rat thoracic aorta.

Shunaoxin pill (SNX), one of the famous classical recipes in traditional Chinese medicine, is developed from the "Decoction of Xionggui". It has been used for treatment of cerebrovascular related diseases. It is well known that vasodilatation plays a very important role in cerebrovascular diseases. The effect of SNX on vasorelaxant activity has not yet been explored. Therefore, we aimed to investigate the vasorelaxant effects of SNX on isolated rat thoracic aorta so as to assess some of the possible mechanisms. We also investigate the gasotransmitter signaling pathway involved which has been rarely reported in isolated rat thoracic aorta before. The present study was performed to examine the vasodilative activity of SNX and its mechanisms in isolated rat thoracic aorta. SNX was studied on isolated rat thoracic aorta in vitro, including endothelium-intact and endothelium-denuded aortic rings. In present study, specific inhibitors including soluble guanylate cyclase (sGC) inhibitor 1 H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ), cyclooxygenase (COX) inhibitor indomethacin (INDO), NO synthase inhibitor NG-nitro-l-arginine methyl ester (L-NAME), heme oxygenase-1 (HO-1) inhibitor zinc-protoporphyrin (ZnPP), cystathionine γ-lyase (CSE) inhibitor DL-Propargylglycine (PAG), non-selective K(+) channel inhibitor tetraethylammonium chloride (TEA), KV channel inhibitor 4-Aminopyridine (4-AP), and KATP channel inhibitor Glibenclamide (Gli) were used, they were added 20min before NE contraction and then added SNX to induce vasodilation. Removal of endothelium or pretreatment of aortic rings (intact endothelium) with L-NAME, ODQ or ZnPP significantly blocked SNX-induced relaxation. Pretreatment with the non-selective K(+) channel inhibitor TEA, KV channel inhibitor 4-AP or the KATP channel inhibitor Gli, none of them had influences on the SNX-induced response (p>0.05). Besides, SNX inhibited the contraction triggered by NE in endothelium-denuded rings in Ca(2+)-free medium. SNX also produced rightward parallel displacement of CaCl2 curves. These results suggest that SNX can induce less endothelium-dependent and more endothelium-independent vascular relaxation. The NO/cGMP and HO/CO pathways, blockade of Ca(2+) channels are inhibition of IP3R mediated Ca(2+) mobilization from intracellular stores, are likely involved in this relaxation. Furthermore, the underlying mechanisms of combined compositions in SNX await further investigations.

Huo L ，Zhang J ，Qu Z ，Chen H ，Li Y ，Gao W ... -  《-》

The anti-hypertensive effect of Danshen (Salvia miltiorrhiza) and Gegen (Pueraria lobata) formula in rats and its underlying mechanisms of vasorelaxation.

Radix Salviae miltiorrhizae (Danshen) and Radix Puerariae lobatae (Gegen) have long been used in traditional Chinese Medicine and serve as the principal herbs in treating cardiovascular disease. In the present study, an aqueous extract comprising Danshen and Gegen in the ratio of 7:3 (DG) was investigated for its anti-hypertension in vivo and vasodilative activities ex vivo. The anti-hypertensive effect of DG extract was investigated in spontaneously hypertensive rat (SHR) by measuring systolic blood pressure (SBP). Oral administration of DG extract was started at age of 6 weeks and 14 weeks for the preventive and therapeutic studies, respectively. Blood pressure was measured by tail-cuff method biweekly for 12 weeks. The ex vivo vasodilative activities of DG extract, its dependency on endothelium and the involvement of nitric oxide, prostacyclin and potassium channels were investigated using isolated rat aorta ring in organ bath. For in vivo study, systolic blood pressure was significantly reduced in DG extract-treated groups (90.2 and 300 mg/kg) as compared with the SHR control in both preventive and therapeutic studies. However, DG extract was unable to suppress or delay the onset of hypertension in the preventive study. For ex vivo study, the results showed that DG extract induced a concentration-dependent relaxation in aorta and persisted response was observed with the removal of endothelium. Besides, pretreatment with a non-selective potassium channel inhibitor tetraethylammonium (TEA) also significantly inhibited DG extract-induced vasodilation. Further investigations on specific potassium channel blockers revealed that ATP-sensitive potassium (K(ATP)) channel inhibitor glibenclamide, inward rectifier potassium (Kir) inhibitor barium chloride and voltage-dependent potassium (K(v)) channel inhibitor 4-aminopyridine, but not BK(Ca) channel inhibitor iberiotoxin, exerted significant inhibition on DG extract-induced vasodilation. The results of in vivo SHR animal model suggested that DG aqueous extract possessed blood pressure lowering effect on both pre- and post-hypertensive rats, which could be explained by its endothelium-independent vasodilation via the opening of K(ATP), Kir and K(v) channels.

Ng CF ，Koon CM ，Cheung DW ，Lam MY ，Leung PC ，Lau CB ，Fung KP ... -  《-》

[Endothelium-dependent vasorelaxation effects induced by apigenin on the thoracic aorta of rats and its possible mechanism].

Sui H ，Zhi Y ，Liu H ，Gao P ，Xu H ，Yan W ... -  《-》

New insights into the mechanisms of the vasorelaxant effects of apocynin in rat thoracic aorta.

Apocynin is a naturally occurring acetophenone widely used as an inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Recent data suggested that apocynin might exert NADPH oxidase-independent pharmacological properties. Among them, vasorelaxant properties have been described, but the mechanisms still give rise to debates. The present study investigated the mechanisms involved in the vasorelaxant effect of apocynin on the in vitro model of rat isolated thoracic aortic rings. Apocynin (30 μM to 10 mM) induced a dose-dependent relaxation in both endothelium-intact and endothelium-denuded aortic rings with respective EC50 values of 0.78 ± 0.08 and 1.91 ± 0.21 mM. Endothelium removal or inhibition of nitric oxide (NO) synthase with N(ω)-nitro-L-arginine-methyl ester (L-NAME) significantly decreased but did not abolish the effect of apocynin. By contrast, apocynin-induced relaxation was unchanged after incubation with indomethacin or charybdotoxin plus apamin. In endothelium-denuded aortas, the vasorelaxant effect of apocynin was significantly reduced by glibenclamide but not by 4-aminopyridine nor by iberiotoxin. Apocynin significantly decreased Ca(2+)-induced contraction and inhibited intracellular Ca(2+) mobilization after contraction with phenylephrine. Finally, the acute intravenous injection of apocynin led to an immediate and transient hypotensive effect in spontaneously hypertensive rats (SHR). In conclusion, our data demonstrated that apocynin induces both endothelium-independent relaxant effects involving inhibition of Ca(2+) mobilization and activation of KATP channels in vascular smooth muscle cells and endothelium-dependent effects mediated by NO. These results should provide a basis for caution when interpreting results on the vascular effects of apocynin.

Senejoux F ，Girard-Thernier C ，Berthelot A ，Bévalot F ，Demougeot C ... -  《-》