Magnetic Susceptibility and Electron Spin Resonance Absorption Spectra of Mouse Melanomas S91 and S91A

Summary

A study of magnetic susceptibility and electron spin resonance (E.S.R.) spectra of Cloudman 591 and 591 A melanomas and various mouse tissues was correlated with trace-meted analysis and known biochemical reactions. Average magnetic moments obtained from temperature-dependence studies showed the following order for tissues: S91 > S91 A > leg muscle. These results indicated a similar order in the. relative concentration of magnetic species (free radicals and/or paramagnetic ions) and were Confirmed by E.S.R. The E.S.R. spectra cit: different power levels showed that the free radical activity cnul the Cu²⁺ and Fe³⁺ activity attributed to different signals was generally higher in S91 them in S91A, which did not show an Fe²⁺ type sisnal. Normal tissues such as liver, spleen, heart, kidney, brain, and leg muscle showed varying amounts of free radical activity but not signals attributable to paramagnetic ions. E.S.R. spectra and trace-metal analysis at different stages of S91, tumor growth indicated a systematic increase in the free rad cal activity, total copper and iron concentrations, and paramagnetic ions, presumed to be Cu²⁺ and Fe³⁺. The S91 A melanoma showed increase in total copper, but not in free radical and paramagnetic ion (Cu²⁺) activity, after the initial growth. Correlation of these findings with known biochemical reactions suggests that the free radical activity may be attributed partly to melanin and intermediates of various enzymatic reactions. Presumed paramagnetic ion activity cannot yet be ascribed to specific biostates.