Seki S, MacLeod K T
Department of Cardiac Medicine, National Heart and Lung Institute, University of London, United Kingdom.
Am J Physiol. 1995 Mar;268(3 Pt 2):H1045-52. doi: 10.1152/ajpheart.1995.268.3.H1045.
Single, enzymatically isolated guinea pig ventricular myocytes were exposed to 3-min periods of anoxia with glucose-free Tyrode solution containing 1 mM sodium dithionite (Na2S2O4) and were then reoxygenated for 10 min. The myocytes were exposed to rapid applications of 10 mM caffeine during the control, anoxic, and reoxygenation periods. Intracellular Ca2+ concentration ([Ca2+]i) was measured ratiometrically using indo 1 with simultaneous measurements of cell length. The effects of anoxia on Ca2+ were compared with those of hypoxia and metabolic inhibition. The amplitude of the electrically stimulated (Ca transient) and caffeine-evoked Ca2+ (Caff-Ca) transients decreased during anoxia and recovered after reoxygenation. Diastolic [Ca2+]i did not change during 3 min of anoxia but rose progressively after prolonged anoxia and remained at this higher level on reoxygenation. During metabolic inhibition the Ca transients decreased, while the Caff-Ca transients showed no change in amplitude. During hypoxia the Ca transients decreased. Anoxia slowed the time to peak of the Ca transient, the time to 50% relaxation, and the time to 90% relaxation. The decline of indo 1 fluorescence on rapid caffeine application was slowed during anoxia, metabolic inhibition, and hypoxia and partially recovered after reoxygenation.
将单个酶分离的豚鼠心室肌细胞暴露于含有1 mM连二亚硫酸钠（Na2S2O4）的无糖台氏液中进行3分钟缺氧处理，然后再复氧10分钟。在对照、缺氧和复氧期间，对肌细胞快速施加10 mM咖啡因。使用indo 1以比率法测量细胞内Ca2+浓度（[Ca2+]i），同时测量细胞长度。将缺氧对Ca2+的影响与缺氧和代谢抑制的影响进行比较。电刺激（Ca瞬变）和咖啡因诱发的Ca2+（Caff-Ca）瞬变的幅度在缺氧期间降低，复氧后恢复。在3分钟缺氧期间，舒张期[Ca2+]i没有变化，但在长时间缺氧后逐渐升高，并在复氧时保持在较高水平。在代谢抑制期间，Ca瞬变降低，而Caff-Ca瞬变的幅度没有变化。在缺氧期间，Ca瞬变降低。缺氧减慢了Ca瞬变达到峰值的时间、50%松弛时间和90%松弛时间。在缺氧、代谢抑制和缺氧期间，快速施加咖啡因时indo 1荧光的下降减慢，复氧后部分恢复。
