苄基四氢巴马汀对心室肌动作电位和延迟整流钾电流的频率依赖性作用

目的　研究BTHP对豚鼠乳头状肌动作电位及单个心室肌细胞延迟整流钾电流影响的频率依赖性。方法　用标准微电极方法在不同基础周长 (BCL)时测定动作电位 ;采用全细胞膜片钳技术测定延迟整流钾电流 (IK:IKr、IKs)。结果　 10 0 μmol·L-1BTHP在BCL为 :2 0 0 0、2 5 0ms时 ,使APD2 0 分别延长 11 35 %和 2 5 5 5 % ;使APD90 分别延长15 97%和 32 5 6 %。 30 μmol·L-1BTHP在刺激频率为 :0 2 5和 2 0Hz时分别使Ikr,tial从 (0 94± 0 .44 ) pA·pF-1和(0 92± 0 31) pA·pF-1降至 (0 6 0± 0 32 ) pA·pF-1和 (0 43± 0 18)pA·pF-1。在刺激频率为 :0 1和 2 0Hz时分别使Iks,tial从 (4 2 2± 0 5 6 ) pA·pF-1和 (5 14± 0 2 8)降至 (2 5 8±0 41)pA·pF-1和 (2 6 2± 0 37)pA·pF-1。结论　BTHP可频率依赖性地阻滞IKr、IKs,其延长动作电位也呈频率依赖性

Frequency dependent effects of benzyltetrahydropalmatine (BTHP) on the action potential and the delayed rectifier potassium current in guinea pig ventricular myocytes

AIM To investigate frequency dependent effects of BTHP on the action potential duration (APD) of papillary muscle and on the delayed rectifier potassium currents ( I K, ie , I Kr , I Ks ) of ventricular myocytes in guinea pig. METHODS Membrane potentials were studied with standard microelectrodes at basic cycle length (BCL) and currents were measured with whole cell patch clamp configuration. RESULTS BTHP 100 μmol·L -1 prolonged APD 20 by 25 51% and 11 35% ,and prolonged APD 90 by 32 56% and 15 84% at BCL of 250 ms and 2000 ms ,respectively. BTHP 30 μmol·L -1 decreased I Kr,tial from (0 94±0 44) pA·pF -1 and (0 92±0 51)pA·pF -1 to (0 60±0 32)pA·pF -1 and (0 43±0 18)pA·pF -1 at frequencies 0 25 Hz and 2 0 Hz. Meanwhile, BTHP (30 μmol·L -1 ) inhibited I Ks,tail from (4 22±0 56)pA·pF -1 and (5 14±0 28)pA·pF -1 to (2 58±0 91)pA·pF -1 and (2 62±0 37)pA·pF -1 at frequencies 0 1 Hz to 2 0 Hz, respectively. CONCLUSION BTHP can block I Kr , I Ks and length APD in a frequency dependent manner.