³¹p nme spectroscopic study of the effects of γ‐irradiation on rif‐1 tumor cells perfused in vitro

Abstract

In order to examine the mechanisms underlying radiation-induced changes in phosphorus metabolite levels observed in RIF-1 tumors in vivo, RIF-1 cells in culture were perfused for up to 70 h following gamma-irradiation with 0-25 Gy and monitored continuously by 31P NMR spectroscopy at 8.5 T. Cells immobilized in the sample volume by incorporation into calcium alginate beads were bioenergetically stable, but did not replicate at the cell density used. Following an initial increase in PCr and NTP, which occurred in both control and irradiated cells, a dramatic decline in high-energy phosphates was detected beginning 24-30 h after irradiation with 15 or 25 Gy. In contrast, unirradiated cells or cells treated with 10 Gy remained metabolically stable for up to 72 h. The metabolic changes induced by irradiation of the cultured cells, which reflected cell death and lysis, were distinctly different from those observed in RIF-1 tumors in vivo during the same postirradiation time interval--an increase in high-energy relative to low-energy phosphates. This suggests that the spectral changes in vivo do not result from direct modification of cellular energy metabolism by radiation injury.

Metabolism of alternative substrates and the bioenergetic status of EMT6 tumor cell spheroids

“…[17][18][19] Perfusate was prewarmed to 40°C and gassed with 95%O 2 /5%CO 2 in a large reservoir and recirculated through the sample from bottom to top at a rate of 6 ml/ min; the spheroids tumbled gently within the sample volume during the experiment. The temperature within the cell chamber (35°C) was regulated by the spectrometer temperature control unit and monitored continuously using a fiber optic temperature sensor (Luxtron, Mountain View CA).…”

Radiotherapeutic Response of Ehrlich Ascites Tumor Cells Perfused in Agarose Gel Threads and Implanted in Mice A 31P MR Spectroscopy Study

“…Potential mechanisms to explain observed spectral changes following tumor irradiation may include tissue effects (such as perfusion, reoxygenation, recruitment of quiescent cells and immune response), direct cellular effects (such as biochemical or cytokinetic changes) and repair of potentially lethal damage [25,34]. 31 P spectra of solid EATC tumor exposed to focal 60 Co gamma rays irradiation also showed a similar pattern of decrease in ␤-ATP/Pi as observed in perfused cells [30].…”

Gel‐entrapment of perfluorocarbons: A fluorine‐19 NMR spectroscopic method for monitoring oxygen concentration in cell perfusion systems

“…Experiments were performed as described previously (18) in a sterile perfusion system. Perfusate was recirculated at 6 ml/min between a 2.1-ml sample chamber ( Fig.…”

“…Experiments were performed as described previously (18) in a sterile perfusion system. Perfusate was recirculated at 6 ml/min between a 2.1-ml sample chamber ( in the headspace above the chamber before being removed by aspiration and returned to the reservoir, which was also gas-equilibrated.…”