title: Vasorelaxant effects of Cerebralcare Granule® are mediated by NO/cGMP pathway, potassium channel opening and calcium channel blockade in isolated rat thoracic aorta.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China.
authors.forename: Zhuo
authors.initials: Z
authors.lastname: Qu
authors.affiliation: Department of Pharmacy, Logistics College of Chinese People׳s Armed Police Forces, Tianjin Key Laboratory of Cardiovascular Remodeling and Target Organ Injury, Tianjin 300162, China.
authors.forename: Jingze
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China. Electronic address: biochemgao@hotmail.com.
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Gao
authors.affiliation: Department of Pharmacy, Logistics College of Chinese People׳s Armed Police Forces, Tianjin Key Laboratory of Cardiovascular Remodeling and Target Organ Injury, Tianjin 300162, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China.
authors.forename: Huimin
authors.initials: H
authors.lastname: Guo
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China.
authors.forename: Tingting
authors.initials: T
authors.lastname: Wang
authors.affiliation: School of Pharmaceutical Science and Technology, Tianjin University, Tianjin 300072, China.
authors.forename: Hongfa
authors.initials: H
authors.lastname: Li
authors.affiliation: The State Key Laboratories of Pharmacodynamics and Pharmacokinetics, Tianjin, China.
authors.forename: Changxiao
authors.initials: C
authors.lastname: Liu
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000008:administration & dosage / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism; D006152:Cyclic GMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal / Q000008:administration & dosage / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D054086:KATP Channels / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D004365:Drugs, Chinese Herbal; D054086:KATP Channels; D015221:Potassium Channels; D014665:Vasodilator Agents; C553222:cerebralcare preparation; D009569:Nitric Oxide; D006152:Cyclic GMP; D002118:Calcium
keywords: Aortic rings; Ca(2+) mobilization; K(+) channel; Nitric oxide; Traditional Chinese medicine; Vasorelaxation