大鼠离体心脏停灌和再灌早期引起的肌酸激酶的双相释放

心脏缺血再灌损伤导致肌酸激酶(CK)的大量释放。本实验提供了一个模型、可对再灌早期CK释放的动态变化进行研究。目的在于试图将停灌损伤和再灌损伤加以区分,并探讨氧反常和钙反常在两种损伤中的相对作用。用Langendorff法灌流大鼠离体心脏,平衡10min,停灌10min。于再灌3min内每15s收集一次冠脉流份,测定CK活性(U/L),作为心肌细胞损伤的指标。再灌3min内CK释放呈双相变化,它们的峰值比平衡期对照值高4-6倍。第Ⅰ峰恒定出现于再灌15s。第Ⅱ峰在有基质Krebs-Henseieit(K-H)溶液灌流组主要出现在再灌30-75s,在无基质K-H溶液灌流组主要出现在再灌120-180s。初步判断,第Ⅰ峰主要代表缺灌损伤,第Ⅱ峰主要代表再灌损伤。缺氧或加葡萄糖灌流均能降低双峰值及总释放量,而低钙灌流仅能延缓第Ⅱ峰的出现。由于葡萄糖能增强细胞对氧反常的耐受性,而缺氧能使氧反常推迟出现,又由于缺灌期胞外液并不缺钙,因此在OK双相释放峰值中可能并不包含典型的钙反常成分,而包含氧反常成分。至于低钙降低第Ⅱ峰的原因,可能是暂时抑制了氧反常造成的钙内流与钙负荷损伤。

THE BIPHASIC CREATINE KINASE RELEASE FROM ISOLATED RAT HEART INDUCED BY GLOBAL ISCHEMIA AND EARLY PERIOD OF REPERFUSION

The present study provided a model with which the kinetics of CK release inthe early phase of reperfusion was investigated. By using Langendroff methodthe isolated rat heart was first perfused for 10 min for establishing equilibrium,then stopped for 10 min to establish global ischemia, and finally followed by reper-fusion for sample collection in every 15 s for the measurement of CK activity (U/L)as an index of cellular damage. A characteristic biphasic release of CK was shownunder condition of 3 min reperfusion with Krebs-Henseleit (K-H) solution withoutglucose. The Ist peak of CK release appeared abruptly in the first 15 s of reperfusionand the 2nd one, during 120--180 s of reperfusion. The appearance of the 2ndpeak was shifted to 30--75 s by adding glucose (11.1 mmol/L) into the perfusate.The 1st peak mainly reflects ischemic injury while the 2nd represents reperfusioninjury. Anoxia (95% N_2+5% CO_2) or glucose addition may delay or decreaseboth peaks, but low Ca~(2+) (0.05 mmol/L) only delays the appearance of the 2ndpeak to 3 min. The results suggst that the oxygen paradox rather than calciumparadox is involved in both phases of CK release. As for low Ca~(2+) decreasingthe 2nd peak may be attributed to its effect of reducing Ca~(2+) inflow andoverload injury secondary to oxygen paradox.