Interactions of polyamines with Mg(2+)-sensitive macroelectrodes and Mg2+ buffers.

The polyamines spermine, spermidine and putrescine interact with Mg(2+)-sensitive macroelectrodes based on the neutral carrier ETH 7025; the interaction in decreasing order being spermine, spermidine and putrescine. The effect is small and dependent on the ionized magnesium concentration ([Mg2+]free), only resulting in a significant increase in the measured [Mg2+]free with spermine and spermidine at [Mg2+]free less than 0.5 mM. The polyamines compete with Mg2+ for common binding sites on Mg2+ buffers such as ATP, ADP and citrate, releasing bound Mg2+ and increasing the [Mg2+]free. This effect is most prominent with Mg ATP and the action of the polyamines in decreasing order is spermine, spermidine and putrescine. Increases in polyamines which occur in cell proliferation and cancer could thus secondarily increase the [Mg2+]free resulting in an activation of Mg(2+)-dependent metabolic pathways.