title: [Acetylcholine contracture of the fast muscle fibers in the lamprey, Lampetra fluviatilis].
abstract: Fast fibers of m. longitudinalis linguae respond to Ach by a transient contracture with a half-decay period of 3-5 sec. The threshold concentration of Ach is approximately 10(-7) g/ml. Ach contracture is based on even depolarization of the whole muscle membrane. Threshold level of the MP for the onset of contracture lies between --50 and --40 mV. In the presence of Ach depolarization decreases twofold within 40-70 sec. Relaxation is not due to the decrease of depolarization. Contraction--Ach concentration curve has a small slope; it reaches maximum at a concentration 10(-4) g/ml, which corresponds to the MP ca. -10mV. Equilibrium Ach potential is significantly shifted to depolarization as compared to that in frog muscles, being equal to +1+/-1.8 mV.
mesh_terms: D000109:Acetylcholine / Q000502:physiology*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005399:Fishes / Q000502:physiology*; D007798:Lampreys / Q000502:physiology*; D008564:Membrane Potentials; D009119:Muscle Contraction; D009132:Muscles / Q000502:physiology*; D011188:Potassium / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D013997:Time Factors
chemical_list: D000109:Acetylcholine; D011188:Potassium
vernacular_title: Atsetilkholinovaia kontraktura bystrykh myshechnykh volokon minogi Lampetra fluviatilis