Electrophysiologic Effects Of GFA On Ventricular Myocytes Of Guinea Pigs And Rats

Objective: The effects of Guanfu Base A (GFA) on ion channel current, which include sodium channel current (I_Na) , delayed rectifier potassium current (I_Ks), inward rectifier potassium current (I_K1), transient outward potassium current(I_to), were evaluated in isolated ventricular myocytes of guinea pigs and rats by using patch clamp whole cell recording techniques to investigate the mechanism of antiarrhythmic action of GFA.Methods: Single ventricular cell was obtained from healthy guinea and rat hearts using enzymatic dissociation techniques. The whole cell patch clamp method was used to record the I_Na,I_K,I_K1 and I_to.Results: (1) At the test potential of -20mV, GFA(50,150,500,750μmol/L) produced 24.24 ± 2.78%, 42.84± 1.39%, 61.23 ±1.34 % and 100±0 %, respevtively, concentration-dependent reduction of I_Na comparing with control, with a mean IC₅₀(50% inhibitory concentration) value of 184.38μmol/L. GFA inhibited sodium channel current in use-dependent manner. 150μmol/L GFA shifted up the current-voltage relation curve (I-V curve) and scaled down the peak I_Na without producing any significant effects on activation threshold (-50mV), peak current potential (-20mV) and the shape of the I-V curve. After the...