CAJ | 학술논문

实验用全细胞膜片钳技术在单个豚鼠心室肌细胞上研究了腺苷(Ado)对正常及异丙肾上腺素 (Iso)致豚鼠心室肌细胞动作电位、迟后除极(DAD)、 L-型钙电流 (ICa.L)和短暂内向电流 (Iti)的作用.结果表明:(1) Ado在20～100 μmol/L时对豚鼠心室肌细胞动作电位和ICa.L 无明显直接作用, 但却可明显降低Iso所致的动作电位时程(APD)延长和ICa.L 峰值增大, Iso (10 nmol/L) 使细胞APD50 从 340±21 ms 延长到486±28 ms (P< 0.01), APD90从 361±17 ms 延长至501±29 ms (P<0.01); ICa.L 峰值从-6.53±1.4 pA/pF 增大到-18.28±2.4 pA/pF (P<0.01), 电流电压曲线明显左移和下移; Ado (50 μmol/L) 使APD50和APD90降至 403±19 ms和419±26 ms, 但并不影响动作电位其它参数, 使ICa.L峰值降低至-10.2±1.5 pA/pF (P<0.01).(2) Iso (30 nmol/L) 可诱发心室肌细胞产生DADs,其发生率为100%; Ado (50 μmol/L) 可完全抑制Iso引发DADs; 细胞经-40～+20 mV、时程2 s的除极电压, Iso (30 nmol/L)诱导出Iti, 其发生率为100%; Ado (50 μmol/L)可明显抑制Iso致Iti的发生, 其发生率降为14.3%.研究结果提示, Ado对豚鼠心室肌细胞动作电位和ICa.L 无明显直接作用, 但却可显著降低Iso 所致APD的延长、 ICa.L 的增加和 Iti 的发生, 从而降低细胞内Ca2+的超载, 此作用是Ado 抑制Iso 致DADs的电生理基础.
실험용전세포막편겸기술재단개돈서심실기세포상연구료선감(Ado)대정상급이병신상선소 (Iso)치돈서심실기세포동작전위、지후제겁(DAD)、 L-형개전류 (ICa.L)화단잠내향전류 (Iti)적작용.결과표명:(1) Ado재20～100 μmol/L시대돈서심실기세포동작전위화ICa.L 무명현직접작용, 단각가명현강저Iso소치적동작전위시정(APD)연장화ICa.L 봉치증대, Iso (10 nmol/L) 사세포APD50 종 340±21 ms 연장도486±28 ms (P< 0.01), APD90종 361±17 ms 연장지501±29 ms (P<0.01); ICa.L 봉치종-6.53±1.4 pA/pF 증대도-18.28±2.4 pA/pF (P<0.01), 전류전압곡선명현좌이화하이; Ado (50 μmol/L) 사APD50화APD90강지 403±19 ms화419±26 ms, 단병불영향동작전위기타삼수, 사ICa.L봉치강저지-10.2±1.5 pA/pF (P<0.01).(2) Iso (30 nmol/L) 가유발심실기세포산생DADs,기발생솔위100%; Ado (50 μmol/L) 가완전억제Iso인발DADs; 세포경-40～+20 mV、 시정2 s적제겁전압, Iso (30 nmol/L)유도출Iti, 기발생솔위100%; Ado (50 μmol/L)가명현억제Iso치Iti적발생, 기발생솔강위14.3%.연구결과제시, Ado대돈서심실기세포동작전위화ICa.L 무명현직접작용, 단각가현저강저Iso 소치APD적연장、 ICa.L 적증가화 Iti 적발생, 종이강저세포내Ca2+적초재, 차작용시Ado 억제Iso 치DADs적전생리기출.
Using whole-cell patch clamp technique this study investigated the effects of adenosine (Ado) on action potential, L-type calcium current (ICa.L), delayed afterdepolarizations (DADs), and transient inward current (Iti) induced by isoproterenol (Iso) in guinea pig isolated single ventricular myocytes. The results showed: (1) Ado alone had no significant direct effects on action potential and ICa.L in guinea pig ventricular myocytes at 20～100 μmol/L. However, Ado significantly attenuated the prolongation of action potential duration (APD) and the increase of the peak amplitude of ICa.L induced by Iso. Iso (10 nmol/L) markedly increased APD50 and APD90 from 340±21 ms to 486±28 ms and from 361±17 ms to 501±29 ms, respectively (P<0.01), and increased the amplitude of ICa.L from -6.53±1.4 pA/pF to -18.28±2.4 pA/pF (P<0.01). The peak potential of current-potential relationship shifted to the left. Ado (50 μmol/L) abbreviated APD50, APD90 to 403±19 ms and 419±26 ms (P<0.01), and decreased the peak amplitude of ICa.L to -10.2±1.5 pA/pF (P<0.01 vs Iso), but did not change resting membrane potential (RMP), action potential amplitude (APA), and overshoot (OS). (2) Iso (30 nmol/L) reproducibly elicited DADs with 100% incidence of DADs under this condition. Ado (50 μmol/L)completely inhibited Iso from inducing DADs. Iso (30 nmol/L) elicited Iti with 2-second depolarizing voltage-clamp pulses rising to +20 mV from a holding potential of -40 mV, the incidence of Iti being 100%, and the Iti was suppressed in the presence of Ado (50 μmol/L) with the incidence of Iti decreased to 14.3% (P<0.05). These data indicate that Ado antagonizes the stimulatory effect of Iso, and that the antiarrhythmic mechanism of Ado preventing Iso-induced DADs is due to the inhibition of intracellular Ca2+ overload through attenuating the prolongation of APD, the enhance of ICa.L and Iti.