title: X-ray diffraction study on mammalian visceral smooth muscles in resting and activated states.
abstract: Structural changes of guinea pig taenia coli and rat anococcygeus muscle during contraction were studied by X-ray diffraction. The diffraction pattern of the taenia coli showed the 14.4-nm myosin reflection, the 5.9-nm actin layer-line and a diffuse equatorial peak at 1/11.4 nm-1. On application of carbachol, the muscle contracted and the intensity of the 14.4-nm reflection showed a concentration-dependent decrease: the maximum decrease was 24% at 2 x 10(-5) M. Such an intensity decrease was not observed in K-contracture (154 mM). The intensity of the 5.9-nm actin layer-line did not change appreciably on activation. The equatorial peak became broader during contraction. The 14.4-nm myosin reflection of the anococcygeus muscle was weak. Its intensity increased by 106% during contraction induced by 2 x 10(-5) M phenylephrine and by 75% during K-contracture. These results suggest that the number of myosin filaments may increase during contraction of rat anococcygeus muscle but not guinea pig taenia coli.
authors.affiliation: Department of Physiology, Jikei University School of Medicine, Tokyo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: S
authors.initials: S
authors.lastname: Takemori
authors.forename: N
authors.initials: N
authors.lastname: Yagi
mesh_terms: D000818:Animals; D002217:Carbachol / Q000494:pharmacology; D006168:Guinea Pigs; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology*; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure*; D009218:Myosins / Q000032:analysis / Q000648:ultrastructure; D010656:Phenylephrine / Q000494:pharmacology; D005082:Physical Exertion / Q000502:physiology; D051381:Rats; D012146:Rest / Q000502:physiology*; D014781:Viscera; D014961:X-Ray Diffraction
chemical_list: D010656:Phenylephrine; D002217:Carbachol; D009218:Myosins