title: Role of cGMP signals in tetramethylpyrazine induced relaxation of the isolated rat aortic strip.
abstract: In the present study, role of guanosine-3',5'-cyclic monophosphate (cGMP) in the vasodilatation of tetramethylpyrazine (TMP), one of the active ingredients of the Chinese herb Chuang-xion, was investigated. We found that the TMP could decrease the vascular tone of isolated rat aorta precontracted with phenylephrine (10(-8) M) in a concentration-dependent manner from 10(-5) M to 10(-3) M. Also, the TMP-induced relaxation was reduced by 1H-(1,2,4)-oxadiazol-(4,3-a)-quinoxalin-1-one (ODQ) or methylene blue, the inhibitor of soluble guanylyl cyclase. Moreover, the vasodilative response to TMP was enhanced significantly in the presence of sildenafil, a well-known inhibitor of phosphodiestrase type 5 that is sensitive to cGMP. In addition, TMP could increase the cGMP level in the isolated aortic rings and TMP-induced vasodilatation was deleted by cGMP-dependent protein kinases (PKG) blockade. These results suggest that relaxation of rat aortic strip by TMP is induced in the cGMP-dependent manner.
authors.affiliation: School of Post-Baccalaureate Chinese Medicine, China Medical University, Taichung City, Taiwan 40402, ROC. tsaicc@mail.cmu.edu.tw
authors.forename: Chin-Chuan
authors.initials: CC
authors.lastname: Tsai
authors.forename: Tung-Yuan
authors.initials: TY
authors.lastname: Lai
authors.forename: Wei-Chan
authors.initials: WC
authors.lastname: Huang
authors.forename: I-Min
authors.initials: IM
authors.lastname: Liu
authors.forename: Shorong-Shii
authors.initials: SS
authors.lastname: Liou
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects* / Q000502:physiology; D006152:Cyclic GMP / Q000502:physiology*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors; D066298:In Vitro Techniques; D008297:Male; D011719:Pyrazines / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D011719:Pyrazines; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D006152:Cyclic GMP; C017953:tetramethylpyrazine