Studies on human uterine cervix and rat uterus using S-, X- and Q-band electron-spin-resonance spectroscopy

Abstract

The detection of a strong ESR signal in samples of normal human cervix has been previously reported; the signal is much reduced or absent in samples of invasive cancer of the cervix. In order to identify the species responsible for the strong signal, X-, S- and Q-band ESR spectroscopy was used. The major signal that is detectable in ground-up samples of cervix preserved at -196.degree. C has features consistent with the presence of a peroxy free radical. Good agreement with the experimental findings was obtained by computer simulation, using values for the g-tensor of gx = 2.002, gy = 2.005 and gz = 2.036. The peroxy radical is produced on grinding the normal cervix samples to a powder under liquid N2, and appears to be formed by modification of a pre-existing O2-containing complex. Control experiments eliminated the possibility that the strong signals seen in frozen powders prepared from normal cervix were artefacts only of the grinding procedure. Experiments with rats in vivo and with cervix samples in vitro are consistent with the conclusion that the peroxy radical is formed by disturbing the cyclooxygenase system that is involved in prostaglandin synthesis.