Effects of high energy shock waves on tumor blood flow and metabolism:31P/1H/2H nuclear magnetic resonance study

Abstract

The effects of high energy shock waves (HESW) on tumor cell metabolism and tumor blood flow were studied in the NU-1 kidney cancer xenograft by multinuclear 1H/2H/31P magnetic resonance spectroscopy. Tumor xenografts were exposed to 800 HESW using an experimental electromagnetic shock wave emitter based on the Siemens Lithostar Plus, which is used for clinical lithotripsy. Exposure of tumors to 800 HESW resulted in a temporary decrease of tumor blood flow (TBF) determined by the 2H NMR monitoring of the 2HO1H wash-out after intratumoral injection. By concomitant recording of 31P and 1H NMR spectra, tumor pH, high-energy phosphates and lactate levels were followed. Tumor treatment with HESW transiently resulted in acidification, ATP decrease, P(i) increase and lactate increase. In contrast, HESW administration adjacent to the tumor did not significantly influence TBF, tumor pH, high-energy phosphates or lactate levels, showing that the observed alterations are caused by an interaction of HESW and tumor tissue. The most likely explanation for these observations is that HESW administration causes local vascular malfunctioning followed by a reduction in oxygen and nutrient supply to the tumor which leads to a decreased aerobic energy metabolism. The results of this study may be used to aid the design of HESW-based therapies.