title: Analysis of the birefringence of the smooth muscle anococcygeus of the rat, at rest and in contraction. I.
abstract: The birefringence of the rat anococcygeus muscle was measured at rest and in contraction. A large increase (+30%) of the optical retardation was observed in muscles fully stimulated by Noradrenaline, in isometric conditions. This was associated with a reduction of the muscle thickness (-12%), so that the birefringence increased by 48%. These changes were reversed upon relaxation. The relationship between the birefringence increase and the mechanical response was investigated as a function of time and of Noradrenaline concentration. Possible origins for the birefringence increase are considered: an increased density of birefringent material, mainly filaments, seems the most likely explanation of the results.
authors.affiliation: Départément de Physiologie, Université Catholique de Louvain Bruxelles, Belgium.
authors.forename: A
authors.initials: A
authors.lastname: Godfraind-De Becker
authors.forename: J M
authors.initials: JM
authors.lastname: Gillis
mesh_terms: D001003:Anal Canal / Q000032:analysis* / Q000502:physiology; D000818:Animals; D001718:Birefringence; D055598:Chemical Phenomena; D002621:Chemistry; D003050:Coccyx / Q000032:analysis* / Q000502:physiology; D003106:Colon / Q000032:analysis / Q000502:physiology; D008297:Male; D009119:Muscle Contraction; D009126:Muscle Relaxation; D009130:Muscle, Smooth / Q000032:analysis / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains