IMPROVED SAMPLE HANDLING FOR CELL STUDIES BY HIGH FREQUENCY EPR

氮氧化物还原实验通常在X波段进行 (8.8-9.5 GHz)，小区数量相对较多(通常为107 百细胞中的L)。如此大量的细胞并不总是 可用于实验。例如，我们感兴趣的是 探讨细胞转化过程中的细胞代谢 腺病毒，当最初只涉及少数细胞时。 此外，在X波段实验中，高浓度的细胞通常 导致样品管中的细胞分布不均匀 最终在漫长的扩散路径中为代谢物和复杂 表观动力学。我们已经展示了(落基山会议， 1994)氮氧化物还原实验中的细胞数量 通过使用W波段(95 GHz)EPR，可以减少到仅900 由伊利诺伊州EPR研究中心(IERC)开发的光谱仪。通过 采用Q值较高的谐振器，仔细取样 定位和线型拟合软件，我们能够减少 这一数字是S在六个细胞中的一个样本。我们已经测量到了减少 T=36.6oC)在X波段(30个L中有3×106个细胞)和 W带(7.5纳米升中有6个细胞)。从W波段测量的速率 实验(3.5x10-16molesxmin-1xcell-1)基本上与 X-带(3.3X10-16molesxmin-1xcell-1)。从… 考虑到信噪比，我们推断有可能 在W波段观察单个细胞对氮氧化物的还原作用。这将会 开辟了测量细胞氧化还原变化的途径，在这种情况下 有几个细胞参与其中。这是一项正在进行的研究。

Nitroxide reduction experiments are usually carried out at X-band (8.8-9.5 GHz) with a relatively large number of cells (typically 107 cells in 100 l). Such a large number of cells is not always available for experimentation. For example, it is of interest to probe the cellular metabolism during their transformation by adenovirus when, initially, only few cells are involved. Additionally, high concentrations of cells in X-band experiments often result in inhomogeneous cell distribution in a sample tube and eventually in long diffusion paths for the metabolites and complicated apparent kinetics. We already showed (Rocky Mountain Conference, 1994) that the number of cells in the nitroxide reduction experiments can be reduced to only 900 by use of a W-band (95 GHz) EPR spectrometer developed at the Illinois EPR Research Center (IERC). By applying a resonator with a higher Q-value, careful sample positioning, and lineshape fitting software we were able to decrease this number to six cell s in a sample. We have measured reduction rate of TEMPONE (T=36.6 oC) at both X-band (3x106 cells in 30 l) and W-band (6 cells in 7.5 nanoliters). The rate measured from W-band experiments (3.5x10-16 molesxmin-1xcell-1) was essentially the same as that found from X-band (3.3X10-16 molesxmin-1xcell-1). From signal-to-noise considerations, we infer that it will be possible to observe nitroxide reduction by a single cell at W-band. This would open the path towards measurements of cell redox changes in which only a few cells participate. This is an ongoing study.