EFFECTIVENESS AND TOXICITY OF SEVERAL DTPA BROADENING AGENTS FOR BIOLOGICAL ESR SPECTROSCOPY

The effectiveness of a standard ESR broadening agent, potassium trioxa latochromiate (CrOx), for use with the spin-label tempone, was compare d to that of diethylenetriaminepentaacetic acid (DTPA) containing an i on (Gd, Cr, Mn, Fe) with a large magnetic moment. Signal attenuation, line broadening, toxicity, and cell membrane permeability were compare d. As a broadening agent, CrOx was most effective, followed by Fe-DTPA . CrOx proved mildly toxic while Gd-DTPA and Fe-DTPA were virtually no ntoxic. The human red blood cell membrane was tested for permeability to Fe- and Gd-DTPA and found to be impermeable to both. In situations where toxicity to cells is critical, the DTPA chelates, particularly F e-DTPA, may prove an acceptable substitute for CrOx. (C) 1996 Academic Press, Inc.