Factors influencing the water proton relaxation in nuclear fractions from tissues of normal and tumor-bearing animals.

Water proton spin-lattice relaxation times (T1) were measured in nuclear fractions from liver, kidney, and spleen tissues from normal and tumor-bearing animals (TBA) at two frequencies. At 9 MHz, the T1 values for TBA nuclear fractions are less than those for normal nuclear fractions, contrary to observations at the cellular level. Trace metal ion concentration and nucleic acid content estimated for these nuclear fractions suggest that the DNA-metal ion interaction might be responsible for the observed differences in the T1 of nuclear fractions at low frequencies.