The first ESR analysis consisted of a carboxy-PTIO solution diluted with PBS pH 7.4.The second solution was composed of diethylamine NONOate (DEA NONOate), a nitric oxide generator, added to a carboxy-PTIO diluted with
potassium biphthalate buffer pH 4.0.A third solution containing streptozotocin in PBS, carboxy-PTIO, and
potassium biphthalate buffer was examined also.A fourth ESR analysis consisted of a solution mixture containing streptozotocin in PBS, carboxy-PTIO, [Cu.sup.++], and ascorbate in potassium mixture biphthalate buffer.