Figure 4.

Troglitazone exerts its positive inotropic effect without increasing Ca²⁺ concentration in perfused hearts. (A and B) Representative tracings of LVP and fura-2 fluorescence ratio in an isovolumic-perfused rat heart before and after treatment with isoproterenol (A), bolus injection of 5 pmol) or troglitazone (B), bolus injection of 1 μmol). (C) The average effect of isoproterenol and troglitazone on LVP_max and Ca²⁺ concentration (n=5, respectively). Although both isoproterenol and troglitazone increased LVP_max, isoproterenol but not troglitazone increased the fura-2 fluorescence ratio. Changes of parameters are expressed as per cent changes from the baseline values (C). ^*P<0.05 vs vehicle.