The effects of levosimendan on [Ca2+]i in guinea-pig isolated ventricular myocytes.

Ca2+-sensitising agents offer a new approach to the treatment of congestive heart failure. This study examined the effects of the Ca2+-sensitising agent, levosimendan, on contraction and [Ca2+]i in guinea-pig ventricular myocytes. Levosimendan 100 nM produced an increase in cell shortening without affecting the [Ca2+]i transient or the Ca2+ content of the sarcoplasmic reticulum. 1 microM levosimendan increased the rate of decay of the [Ca2+]i transient and increased the Ca2+ content of the sarcoplasmic reticulum. These results suggest that at therapeutically relevant concentrations levosimendan can produce a significant inotropic effect without affecting [Ca2+]i but at higher concentrations may also inhibit phosphodiesterase.