Tamulevicius P, Schmidt K, Streffer C
Radiat Res. 1984 Oct;100(1):65-77.
The effects of X irradiation and/or hyperthermia on both the intrinsic and total poly(ADPR)synthetase activity in permeabilized human melanoma cells were determined. All treatments were given in the early phase of exponential growth (early log phase). The intrinsic and total enzyme activities were significantly decreased immediately after heat treatment at either 42 degrees or 44 degrees C for 3 hr. These activities remained below the respective control levels over the whole period of culture, and some recovery was observed after 48 hr in both cases. X-ray doses of 3.76 to 11.28 Gy produced an increase in intrinsic activity 30 min postradiation (p.r.) but had no significant effect on the total activity. The increase may thus be associated with DNA repair. At later times after irradiation with 3.76 Gy no significant changes were observed. Combined treatment of X irradiation (3.76 Gy) followed by hyperthermia (42 degrees C for 3 hr) produced an enhanced decrease in intrinsic activity, equivalent to that after hyperthermia at 44 degrees C. The effects on cell proliferation were similar in both cases. However, the total activity was not modified to the same extent after combined treatment. The long-term decrease in total activity at 42 degrees C hyperthermia may be due to inhibitors produced during heat treatment since the enzyme activity was partially restored by changes of fresh medium. These results suggest that heat, X irradiation, and combined treatment act in a different manner on the chromatin-associated enzyme or at different sites on the enzyme complex.
测定了X射线照射和/或热疗对人黑色素瘤通透细胞中内源性和总聚（ADP - 核糖）合成酶活性的影响。所有处理均在指数生长早期（对数早期）进行。在42℃或44℃热处理3小时后，内源性和总酶活性立即显著降低。在整个培养期间，这些活性一直低于各自的对照水平，并且在两种情况下48小时后均观察到一定程度的恢复。3.76至11.28 Gy的X射线剂量在辐射后30分钟（p.r.）使内源性活性增加，但对总活性无显著影响。因此，这种增加可能与DNA修复有关。在用3.76 Gy照射后的后期，未观察到显著变化。先进行X射线照射（3.76 Gy）然后热疗（42℃，3小时）的联合处理使内源性活性的降低增强，等同于44℃热疗后的降低。两种情况下对细胞增殖的影响相似。然而，联合处理后总活性没有在相同程度上受到影响。42℃热疗后总活性的长期降低可能是由于热处理过程中产生的抑制剂，因为更换新鲜培养基后酶活性部分恢复。这些结果表明，热、X射线照射和联合处理对染色质相关酶或以酶复合物上不同位点的作用方式不同。
