Troponin C-mediated calcium sensitization by levosimendan accelarates the proportional development of isometric tension

摘要: The effects of various calcium sensitizers on myosin-actin crossbridge kinetics were evaluated in intact, paced guinea-pig papillary muscle by analysing the velocity development isometric tension (dT/d t ) detail. effect association (the whole sequence events from troponin onward) and dissociation rates crossbridges was estimated rising phase early normalized dT/d curve. Levosimendan, a sensitizer acting through C, accelerated proportional rare decelerated rate crossbridges. levosimendan occurred before peak twicht achieved. Thus, compound did not change actual relaxation twitch tension. Since more pronounced than crossbridges, shifted entire curve to left. Based analysis seems act prefenrentially as at low concentrations. At high concentrations phosphodiesterase III (PDE III) inhibitory properties modulated its processes. In contrast, PDE inhibition is probably primary mechanism action for MCI-154, Pimobendan, EMD 53998 concentrations, whereas their direct crossbrige contributed positive inotropic sensitizing meachanisms these compounds seemed be based almost exclusively decelerating