title: Epigallocatechin gallate attenuates ET-1-induced contraction in carotid artery from type 2 diabetic OLETF rat at chronic stage of disease.
abstract: OBJECTIVE
  There is a growing body of evidence suggesting that epigallocatechin gallate (EGCG), a major catechin isolated from green tea, has several beneficial effects, such as anti-oxidant and anti-inflammatory activities. However, whether treatment with EGCG can suppress the endothelin-1 (ET-1)-induced contraction in carotid arteries from type 2 diabetic rats is unknown, especially at the chronic stage of the disease. We hypothesized that long-term treatment with EGCG would attenuate ET-1-induced contractions in type 2 diabetic arteries.
  
  
  METHODS
  Otsuka Long-Evans Tokushima fatty (OLETF) rats (43 weeks old) were treated with EGCG (200 mg/kg/day for 2 months, p.o.), and the responsiveness to ET-1, phenylephrine (PE), acetylcholine (ACh) and sodium nitroprusside (SNP) was measured in common carotid artery (CA) from EGCG-treated and -untreated OLETF rats and control Long-Evans Tokushima Otsuka (LETO) rats.
  
  
  RESULTS
  In OLETF rats, EGCG attenuated responsiveness to ET-1 in CA compared to untreated groups. However, EGCG did not alter PE-induced contractions in CA from OLETF rats. In endothelium-denuded arteries, EGCG did not affect ET-1-induced contractions in either the OLETF or LETO group. Acetylcholine-induced relaxation was increased by EGCG treatment in CA from the OLETF group. The expressions of ET receptors, endothelial nitric oxide synthase, superoxide dismutases, and gp91(phox) [an NAD(P)H oxidase component] in CA were not altered by EGCG treatment in either group.
  
  
  CONCLUSIONS
  Our data suggest that, within the timescale investigated here, EGCG attenuates ET-1-induced contractions in CA from type 2 diabetic rats, and one of the mechanisms may involve normalizing endothelial function.
authors.affiliation: Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Ryusuke
authors.initials: R
authors.lastname: Kawamura
authors.affiliation: Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Taguchi
authors.affiliation: Department of Physiology and Morphology, Institute of Medicinal Chemistry, Hoshi University, Shinagawa-ku, Tokyo 142-8501, Japan. Electronic address: tkoba@hoshi.ac.jp.
authors.forename: Tsuneo
authors.initials: T
authors.lastname: Kobayashi
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D002339:Carotid Arteries / Q000187:drug effects / Q000503:physiopathology*; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D002908:Chronic Disease; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000503:physiopathology*; D019332:Endothelin-1; D066298:In Vitro Techniques; D008297:Male; D019255:NADPH Oxidases / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009599:Nitroprusside / Q000494:pharmacology; D010656:Phenylephrine; D020334:Rats, Inbred OLETF; D017466:Receptors, Endothelin / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014661:Vasoconstriction / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects
chemical_list: D019332:Endothelin-1; D017466:Receptors, Endothelin; D009599:Nitroprusside; D010656:Phenylephrine; D002392:Catechin; C045651:epigallocatechin gallate; D052250:Nitric Oxide Synthase Type III; D013482:Superoxide Dismutase; D019255:NADPH Oxidases; D000109:Acetylcholine
keywords: Carotid artery; EGCG; ET-1; Type 2 diabetes; Vasoconstriction