Potentiation of Hyperthermic Effects Using Hydralazine

抄録

It is said that the efficacy of hyperthermia for malignancies depend on various vasophsiological factors in the tumor, such as pH, blood flow and oxygen tension (p02). The present animal experiment was performed to ascertain how the effect of hyperthermia can be enhanced by administration of hydralazine (HYD), a vasodilator, wich is known to decrease the local blood flow selectively and accordingly, decelerate thermal diffusion in the tumor. HYD (2-5mg/kg) was injected intraperitoneally 20 min before hyperthermia, which was done for 20-30 min at 43°C by the use of a thermo-static water bath. The tumor quadrupling time was 4.5 days in the untreated FM3A group, 5.4 days in the HYD treated FM3A group, 8.5 days in the heat alon FM3A group and 11.2 days in the HYD plus heat treated FM3A group. Those in the respective SCC-VII group were 7.7 days, 9.0 days, 11.1 days and 14.0 days. The enhancement ratio was 2.48 in the treatment for FM3A tumor and 1.81 in the treatment for SCC-VII tumor. Thus, these results indicate that HYD can increase the therapeutic efficiency of local hyperthermia treatment by inducing the change of microenvironment i. e. low pH, tumor hypoxia, deficient nutrition secondary to blood flow diminution which increase the sensitivity of tumor to heat.