Yeung T K, Lauk S, Simmonds R H, Hopewell J W, Trott K R
CRC Normal Tissue Radiobiology Group, (University of Oxford), Churchill Hospital, United Kingdom.
Radiat Res. 1989 Sep;119(3):489-99.
The hearts of mature male rats of the Wistar and Sprague-Dawley strains were locally irradiated with single doses of 17.5 and 20.0 Gy of X rays, respectively. These two dose levels had previously been shown to result in a comparable latent period between irradiation and the death of rats of these two strains from cardiac failure. Morphological changes in the myocardium and modifications in cardiac function were assessed in the animals at 28, 70, and 100 days after irradiation. The first radiation-induced change which was observed in the myocardium was a rapid decline in capillary density and a loss of alkaline phosphatase activity by the capillary endothelial cells. The capillary density was reduced to approximately 50% of that of unirradiated control values at 28 days and to approximately 40% of the control values between 70 and 100 days after irradiation. The loss of enzyme activity was also detected at 28 days. Examination of histological sections showed an increase by 70 days in the areas with negative enzyme activity up to approximately 70% of the myocardium. The reduction in capillary density and the loss of enzyme activity occurred before any marked pathological changes were seen in the myocardium. The pathological lesions seen in the myocardium at 100 days after irradiation were qualitatively and quantitatively the same in the two strains of rat. Measurements of cardiac output in Sprague-Dawley rats showed a gradual decline in output after irradiation; however, measurements in Wistar rats showed a progressive increase in cardiac output over the same period of time. It was shown by rubidium extraction that there was an increase in the percentage of the total cardiac output distributed to the ventricular muscle of Sprague-Dawley rats, while similar measurements in Wistar rats showed no significant change. In spite of the marked strain differences observed in cardiac output and rubidium extraction, blood perfusion per gram of ventricular muscle was apparently not modified in both strains of rat after irradiation. These findings indicated that the correlation between morphological effects after irradiation and the functional expression of damage is highly complex.
分别用17.5 Gy和20.0 Gy的单剂量X射线对Wistar和Sprague-Dawley品系的成年雄性大鼠心脏进行局部照射。此前已表明，这两个剂量水平会导致这两个品系的大鼠在照射后至因心力衰竭死亡之间有相当的潜伏期。在照射后第28、70和100天对动物的心肌形态变化和心脏功能改变进行评估。在心肌中观察到的第一个辐射诱导变化是毛细血管密度迅速下降以及毛细血管内皮细胞碱性磷酸酶活性丧失。照射后第28天，毛细血管密度降至未照射对照值的约50%，在照射后70至100天降至对照值的约40%。在第28天也检测到酶活性丧失。组织学切片检查显示，到70天时，酶活性阴性区域增加至心肌的约70%。在心肌出现任何明显病理变化之前，毛细血管密度就已降低且酶活性丧失。照射后100天在心肌中观察到的病理损伤在这两个品系的大鼠中在定性和定量上是相同的。对Sprague-Dawley大鼠的心输出量测量显示，照射后输出量逐渐下降；然而，对Wistar大鼠的测量显示，在同一时间段内心输出量逐渐增加。通过铷摄取显示，Sprague-Dawley大鼠分配到心室肌的总心输出量百分比增加，而对Wistar大鼠的类似测量显示无显著变化。尽管在心输出量和铷摄取方面观察到明显的品系差异，但照射后两个品系大鼠每克心室肌的血液灌注显然未改变。这些发现表明，照射后的形态学效应与损伤的功能表达之间的相关性非常复杂。
