title: Heartworm extract induces relaxation of isolated rat thoracic aorta.
abstract: Isolated rat thoracic aortic strips undergoing noradrenaline-induced contraction were treated with an adult heartworm (HW) crude extract and then examined for isometric changes in tension. HW extract caused relaxation of endothelium-intact strips, but not endothelium-denuded strips. This effect was inhibited by treatment with NG-nitro-L-arginine methyl ester hydrochloride (L-NAME) and could be reversed by additional treatment with L-arginine. However, HW extract at a high concentration caused slight relaxation of endothelium-denuded strips, and relaxation persisted after L-NAME treatment in endothelium intact-strips. These data suggested that the relaxation induced by HW extract was mainly endothelium-dependent, nitric oxide-mediated, but in part, also endothelium-independent. In addition, a bioassay using isolated rat thoracic aortas may be a useful tool for investigating vasoactive substances in the HW extract.
authors.affiliation: Laboratory of Veterinary Parasitology, Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, 1-1 Yanagido, Gifu 501-1193, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Kitoh
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Nakamura
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Kitagawa
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Unno
authors.forename: Seiichi
authors.initials: S
authors.lastname: Komori
authors.forename: Shin-Pin
authors.initials: SP
authors.lastname: Chiou
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Takashima
mesh_terms: D000818:Animals; D001013:Aorta, Thoracic / Q000187:drug effects*; D004183:Dirofilaria immitis / Q000737:chemistry*; D004285:Dogs; D004730:Endothelium, Vascular / Q000187:drug effects; D005260:Female; D008297:Male; D009126:Muscle Relaxation / Q000187:drug effects*; D009131:Muscle, Smooth, Vascular / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D046509:Tissue Culture Techniques; D014020:Tissue Extracts / Q000494:pharmacology*
chemical_list: D014020:Tissue Extracts