Connelly C M, Vogel W M, Wiegner A W, Osmers E L, Bing O H, Kloner R A, Dunn-Lanchantin D M, Franzblau C, Apstein C S
Circ Res. 1985 Oct;57(4):562-77. doi: 10.1161/01.res.57.4.562.
Early reperfusion after a coronary occlusion may reduce myocardial infarct size, but late reperfusion into necrotic myocardium may alter post-infarction healing. In rabbits, we compared 1- or 3-week-old scars resulting from permanent coronary occlusion to those resulting from a 1- or 3-hour occlusion followed by reperfusion. Reperfusion at 1 hour post-occlusion did not affect scar mechanical properties assessed at 1 week post-infarction, but at 3 weeks post-infarction, these scars had a tensile strength significantly lower than those not reperfused (78 +/- 11 vs. 158 +/- 15 g/mm2, P less than 0.001). They also were composed of a mixture of fibrous tissue (58 +/- 8%) and myocytes (43 +/- 8%) with a hydroxyproline content of 23 +/- 2.5 mg/g dry weight. The nonreperfused scars had a higher proportion of fibrous tissue (73 +/- 3%) by histological evaluation and a 35% higher hydroxyproline content (31 +/- 2 mg/g dry weight, P less than 0.001) than the scars reperfused after 1 hour. In contrast, 3-week-old scars resulting from "late" reperfusion at 3 hours post-occlusion were similar to nonreperfused scars in fibrous tissue composition and hydroxyproline content. Nonetheless, the tensile strength of these scars reperfused 3 hours post-occlusion was significantly less than that of the nonreperfused scars (72 +/- 5 vs. 158 +/- 15 g/mm2, P less than 0.001). The lower tensile strength was associated with a lower collagen cross-link density in this reperfused group of scars. At physiological stress levels (approximately 3 g/mm2), all groups of reperfused and nonreperfused scars had similar mechanical properties in terms of natural strain, stiffness, creep, and stress relaxation. Thus, although the reperfused scars ruptured more easily at high stresses, when assessed at physiological stresses their mechanical properties were not significantly different from those of nonreperfused scars.
冠状动脉闭塞后的早期再灌注可能会减小心肌梗死面积，但对坏死心肌的晚期再灌注可能会改变梗死后的愈合过程。在兔实验中，我们比较了永久性冠状动脉闭塞导致的1周或3周龄瘢痕与闭塞1小时或3小时后再灌注导致的瘢痕。闭塞后1小时进行再灌注并不影响梗死后1周评估的瘢痕力学性能，但在梗死后3周，这些瘢痕的抗张强度明显低于未再灌注的瘢痕（78±11 vs. 158±15 g/mm2，P<0.001）。它们还由纤维组织（58±8%）和心肌细胞（43±8%）混合组成，羟脯氨酸含量为23±2.5 mg/g干重。通过组织学评估，未再灌注的瘢痕纤维组织比例更高（73±3%），羟脯氨酸含量比1小时后再灌注的瘢痕高35%（31±2 mg/g干重，P<0.001）。相比之下，闭塞后3小时“晚期”再灌注导致的3周龄瘢痕在纤维组织组成和羟脯氨酸含量方面与未再灌注的瘢痕相似。尽管如此，闭塞后3小时再灌注的这些瘢痕的抗张强度明显低于未再灌注的瘢痕（72±5 vs. 158±15 g/mm2，P<0.001）。较低的抗张强度与该再灌注瘢痕组中较低的胶原交联密度有关。在生理应力水平（约3 g/mm2）下，所有再灌注和未再灌注瘢痕组在自然应变、刚度、蠕变和应力松弛方面具有相似的力学性能。因此，尽管再灌注瘢痕在高应力下更容易破裂，但在生理应力下评估时，它们的力学性能与未再灌注瘢痕没有显著差异。
