Dimethyl Amiloride Between Activation Of Na <sup> + </ Sup> / Ca <sup> 2 + </ Sup>

Objective: To study the effect of DMA on membrane ionic currents (Sodium-calcium exchange, L-type calcium current , sodium current , transient outward potassium curren, inward rectifier potassium current) between normal and heart failure myocytes of rats. Methods:Whole cell patch-clamp measurements.The effect of DMA on main ionic currents were observed in isolated ventricular myocytes of normal and heart failure rats.Results:1. DMA ( 0.1-3μmol/L) have no significant effects on ICa-L , INa, Ito, IK1 in ventricular myocytes from normal rats.2. DMA ( 0.1-3μmol/L) can agitate INa/Ca.For normal rats: DMA increased outward INa/Ca from 1.99±0.12 to 2.22±0.18,2.62±0.41,2.69±0.57,2.75±0.57 at the potential +50mV, changed 12.28±7.34%,31.56±11.1%,38.36±5.34%,39.28±3.78%; DMA increased inward INa/Ca from-2.38±0.44 to -2.71±0.64, -2.93±0.67, -3.15±0.61, -3.76±0.80 at the potential -100mV, changed 13.80±3.54%, 23.35±5.79%, 35.52±13.26%, 58.41±18.90%. For heart failure rats: DMA increased outward INa/Ca from 2.12±0.37 to 2.34±0.37,2.77±0.38,3.24±0.23,3.64±0.22 at the potential +50mV, changed 10.78±4.73%, 31.47±5.47%, 55.60±16.84%, 75.01±19.74%; DMA increased inward INa/Ca from -2.33±0.33 to -2.76±0.36, -3.06±0.29, -3.57±0.33, -4.49±0.27 at the potential -100mV, changed 19.00±6.29%,33.51±20.17%,55.49±22.56%,94.77±15.75%.Conclusions:1. DMA ( 0.1-3μmol/L) have no significant effects on ICa-L ,INa,Ito and IK1 in ventricular myocytes from normal rats.2. DMA ( 0.1-3μmol/L) can increase the INa/Ca in isolated ventricular myocytes from normal and heart failure rats, and the amplitude of inward INa/Ca is greater than that of outward INa/Ca.