CAJ | 학술논문

本文旨在研究急性低温/再复温对大鼠心室肌膜电位和钾电流的影响.膜电位和膜电流分别在全细胞膜片钳的电压钳和电流钳模式下记录.当细胞外灌流液从25℃降低到4℃后,一过性外向电流(transient outward current, Ito)完全消失,膜电位为+60mV时的稳态外向K+电流(sustained outward K+ current, Iss)和膜电位为-120mV时的内向整流K+电流(inward rectifier K+ current, IK1)分别降低(48.5±14.1)%和(35.7±18.2)%,同时,膜电位绝对值降低.当细胞外灌流液从4℃再升高到36℃后,膜电位出现一过性超级化,然后恢复到静息电位水平;在58个细胞中,有36个细胞伴随复温出现ATP-敏感性K+ (ATP-sensitive K+, KATP)通道的激活.再复温引起的上述变化可以被Na+/K+-ATP酶抑制剂哇巴因(100μmol/L)所抑制.再复温引起的KATP通道激活也能被蛋白激酶A抑制剂H-89(100μmol/L)所抑制.在细胞膜电位被钳制在0mV时,当细胞外灌流液温度从25℃降低到4℃后,细胞的体积没有发生明显改变,但当再复温引起KATP通道激活后,细胞很快发生皱缩,同时细胞内部出现许多折光较强的斑点.上述结果表明急性低温/再复温对大鼠心室肌膜电位和K+电流有明显影响,并提示KATP通道激活可能与心肌低温/再复温损伤有关.
본문지재연구급성저온/재복온대대서심실기막전위화갑전류적영향.막전위화막전류분별재전세포막편겸적전압겸화전류겸모식하기록.당세포외관류액종25℃강저도4℃후,일과성외향전류(transient outward current, Ito)완전소실,막전위위+60mV시적은태외향K+전류(sustained outward K+ current, Iss)화막전위위-120mV시적내향정류K+전류(inward rectifier K+ current, IK1)분별강저(48.5±14.1)%화(35.7±18.2)%,동시,막전위절대치강저.당세포외관류액종4℃재승고도36℃후,막전위출현일과성초급화,연후회복도정식전위수평;재58개세포중,유36개세포반수복온출현ATP-민감성K+ (ATP-sensitive K+, KATP)통도적격활.재복온인기적상술변화가이피Na+/K+-ATP매억제제왜파인(100μmol/L)소억제.재복온인기적KATP통도격활야능피단백격매A억제제H-89(100μmol/L)소억제.재세포막전위피겸제재0mV시,당세포외관류액온도종25℃강저도4℃후,세포적체적몰유발생명현개변,단당재복온인기KATP통도격활후,세포흔쾌발생추축,동시세포내부출현허다절광교강적반점.상술결과표명급성저온/재복온대대서심실기막전위화K+전류유명현영향,병제시KATP통도격활가능여심기저온/재복온손상유관.
The effects of acute cooling/rewarming on cardiac K+ currents and membrane potential were investigated. Membrane potential and current were assessed with whole-cell patch-clamp technique in current-and voltage-clamp modes. When the temperature of bath solution was decreased from 25℃ to 4℃, the transient outward current (Ito) was completely abolished, the sustained outward K+ current (Iss) at +60mV and the inward rectifier K+ current (IK1) at-120mV were depressed by (48.5±14.1)% and (35.7±18.2)%, respectively, and the membrane potential became more positive. After the temperature of bath solution was raised from 4℃ to 36℃, the membrane potential exhibited a transient hyperpolarization and then was maintained at a stable level. In some myocytes (36 out of 58), activation of the ATP-sensitive K+ (KATP) channels after rewarming was observed. The rewarming-induced change in the membrane potential was inhibited by the Na+/K+-ATPase inhibitor ouabain (100μmol/L), and the rewarming-elicited activation of KATP channels was inhibited by the protein kinase A inhibitor H-89 (100μmol/L). Moreover, decrease of the temperature from 25℃ to 4℃ did not induce any significant change in cell volume when the cell membrane potential was clamped at O mV. However, significant ceil shrinkage with spots was observed soon after rewarming-induced activation of KATP channels. These data demonstrate that acute cooling/rewarming has a profound influence on the membrane potential and K+ currents of ventricular myocytes, and suggest that activation of KATP channels may play a role in cardiac cooling/rewarming injury.