EFFECTS OF DICARBOXYETHENYLGERMANIUM SESQUIOXIDE ON ELECTRICAL AND MECHANICAL ACTIVITY IN ISOLATED GUINEA PIG AND RABBIT HEART

The effects of dicarboxyethenylgermanium sesquioxide (DCG) on electrical and mechanical activity in isolated guinea pig papillary muscles and rabbit sinus node were studied by intracellular capillary glass electrode. The effects of DCG on slow action potential and contractile force(Fc) of preparations in which the fast Na⁺ channels were inactived by partial depolarization by increasing the concentration of K⁺ 25.4 mmol/L were observed. DCG (0.5 mol/L) increased Vmax and APA of fast action potential of guinea pig papillary muscles, but its Fc decreased from 105±12% of control to 80±16%. DCG prolonged the spontaneous cycle length (SCL) and APD₉₀ of rabbit sinus node, but the slope of phase 4(SP₄) was lowered. The functional refractory period(FRP) of rabbit left atria was determined by the paired stimulus method. In experiments involving one drug, the drug was added until equilibrium had been reached. It has been demonstrated by experiments that the administration of DCG resulted in an increase of atrial FRP. These findings suggest that the Ca²⁺ inward currents and the K⁺ outward current may be inhibited by DCG.