Nitroxides and malignant human tissues: electron spin resonance in colorectal neoplastic and healthy tissues

Healthy and neoplastic colorectal human tissues of as many as 12 patients h ave been studied, immediately after surgery, by electron spin resonance (ES R) of stable nitroxides at physiological temperature. Cells were maintained in a living state using the McCoy's 5A culture medium. The very low concen tration changes of hydrophilic and lipophilic nitroxides allowed us to esta blish that the response to the oxidative stress induced by the occurrence o f nitroxides in healthy and tumor cells was very weak, thus suggesting thes e compounds are good candidates for contrast enhancement agents in magnetic resonance imaging of colorectal tumor. The analysis of the computed ESR li ne shape of lipophilic nitroxides in both healthy and malignant cells of th e same patient agreed for an unmodified physical status of the membranes wh ere they were mainly localized. The results reported here proved that the c omparison between ESR results must be made in tissues from the same patient and that the physical status of the membranes depended more on the patient history than on changes in the colorectal cell membrane fluidity induced b y the neoplastic process. (C) 1999 Elsevier Science B.V. All rights reserve d.