caa a22 4500 475744926 CHVBK 20180406123510.0 cr unu---uuuuu 170329e20001001xx s 000 0 eng 10.1023/A:1005673708161 doi (NATIONALLICENCE)springer-10.1023/A:1005673708161 Crossbridge kinetics in single frog muscle fibres in presence of ethylene glycol [Elektronische Daten] [M. Bagni, G. Cecchi, B. Colombini, F. Colomo] Single fibres isolated from frog muscle were tetanically stimulated at 14°C to produce isometric tetani at a sarcomere length of about 2.16 μm, using a striation follower device to measure the sarcomere length of a selected segment of fibre. Force-velocity data were obtained by applying ramp releases at pre-set velocity at the tetanus plateau. Sarcomere stiffness was measured at isometric plateau and during isotonic shortening by using sinusoidal length changes at 2 kHz frequency and about 1 nm per half sarcomere (hs) peak to peak amplitude. A correction method was used to compensate for the force truncation due to the quick recovery. After data collection, the bathing solution was substituted with Ringer plus ethylene glycol (EG) at 2 M (11.2% v/v). When the fibre was fully equilibrated with the new solution, the measurements were repeated. Ethylene glycol reduced the speed of the tetanus rise and tetanus relaxation without altering the isometric tension, and reduced the maximum shortening velocity by about 20%. During isotonic contraction tension and stiffness at each given shortening velocity were reduced by about the same amount, so that the stiffness/tension ratio remained almost unaltered. Force-velocity and stiffness data in both standard and EG Ringer were analysed in terms of a two state model (Huxley, 1957). The analysis showed that our results can be accounted for by assuming that EG at 2 M concentration reduces all the rate constants for crossbridges interaction by about the same amount. Kluwer Academic Publishers, 2000 Bagni M. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut Cecchi G. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut Colombini B. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut Colomo F. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/7(2000-10-01), 629-637 0142-4319 21:7<629 2000 21 10974 https://doi.org/10.1023/A:1005673708161 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1005673708161 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Bagni M. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut NATIONALLICENCE 700 1- Cecchi G. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut NATIONALLICENCE 700 1- Colombini B. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut NATIONALLICENCE 700 1- Colomo F. Dipartimento di Scienze Fisiologiche, Viale G.B. Morgagni, 63, I-50134, Firenze, Italy aut NATIONALLICENCE 773 0- Journal of Muscle Research & Cell Motility Kluwer Academic Publishers 21/7(2000-10-01), 629-637 0142-4319 21:7<629 2000 21 10974 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer