title: Vasorelaxant Action of the Chloroform Fraction of Orthosiphon stamineus via NO/cGMP Pathway, Potassium and Calcium Channels.
abstract: Orthosiphon stamineus Benth. (Lamiaceae) is an important plant in traditional folk medicine that is used to treat hypertension and kidney stones. In humans, this plant has been tested as an addition regiment for antihypertensive treatment. Among the treatments for hypertension, O. stamineus had been to have diuretic and vasorelaxant effects in animal models. There is still very little information regarding the vasorelaxant effect of O. stamineus. Therefore, the present study was designed to investigate the vasorelaxant activity and mechanism of action of the fractions of O. stamineus. The vasorelaxant activity and the underlying mechanisms of the chloroform fraction of the 50% methanolic extract of O. stamineus (CF) was evaluated on thoracic aortic rings isolated from Sprague Dawley rats. CF caused relaxation of the aortic ring pre-contracted with phenylephrine in the presence and absence of endothelium, and pre-contracted with potassium chloride in endothelium-intact aortic ring. In the presence of endothelium, both indomethacin (a nonselective cyclooxygenase inhibitor) and [Formula: see text]-[1,2,4]Oxadiazolo[4,3-[Formula: see text]]quinoxalin-1-one (ODQ, selective soluble guanylate cyclase inhibitor) had a small effect on the vasorelaxation response. On the other hand, in the presence of Nω-nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase inhibitor), methylene blue (cyclic guanosine monophosphate lowering agent), tetraethylammonium ([Formula: see text], nonselective calcium activator [Formula: see text] channel blocker), 4-aminopyridine (4-AP, voltage-dependent [Formula: see text] channel blocker), barium chloride ([Formula: see text], inwardly rectifying [Formula: see text] channel blocker), glibenclamide (nonspecific ATP-sensitive [Formula: see text] channel blocker), atropine (muscarinic receptor blocker) and propranolol (β-adrenergic receptor blocker), the vasorelaxant effect significantly reduced the relaxation stimulated by CF. CF was also found to be active in reducing [Formula: see text] release from the sarcoplasmic reticulum and blocking calcium channels.
authors: * College of Pharmacy, Fujian University of Traditional Chinese Medicine, 1 Qiuyang Road, Shangjie, Minhou, Fuzhou 350122, Fujian, P.R. China.|† School of Pharmaceutical Sciences, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia.
authors: Mun Fei
authors: MF
authors: Yam
authors: † School of Pharmaceutical Sciences, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia.
authors: Chu Shan
authors: CS
authors: Tan
authors: † School of Pharmaceutical Sciences, Universiti Sains Malaysia, Pulau Pinang 11800, Malaysia.
authors: Mariam
authors: M
authors: Ahmad
authors: * College of Pharmacy, Fujian University of Traditional Chinese Medicine, 1 Qiuyang Road, Shangjie, Minhou, Fuzhou 350122, Fujian, P.R. China.
authors: Shibao
authors: S
authors: Ruan
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects / Q000378:metabolism; D002121:Calcium Channel Blockers; D015220:Calcium Channels / Q000378:metabolism*; D005591:Chemical Fractionation; D002725:Chloroform; D006152:Cyclic GMP / Q000378:metabolism*; D006973:Hypertension / Q000188:drug therapy; D066298:In Vitro Techniques; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D031342:Orthosiphon / Q000737:chemistry*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology* / Q000627:therapeutic use; D011188:Potassium / Q000378:metabolism*; D017207:Rats, Sprague-Dawley; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D014664:Vasodilation / Q000187:drug effects*; D014665:Vasodilator Agents
chemical_list: D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010936:Plant Extracts; D014665:Vasodilator Agents; D009569:Nitric Oxide; D002725:Chloroform; D006152:Cyclic GMP; D011188:Potassium
keywords: Orthosiphon stamineus; Potassium and Calcium Channels; Vasorelaxation