Phospholipase C activity reduces free magnesium concentration.

The events leading to decline of intracellular free magnesium concentration following traumatic brain injury are unknown. One possible mechanism that may lead to such declines is an alteration in the number and nature of magnesium binding sites within cell membranes following a traumatic event. Although both alterations in membrane structure and decrease in free magnesium concentration have been independently demonstrated to occur following brain trauma, no correlations between the two events have been shown. In the present study, rat brain phospholipids were extracted and reconstituted in MgATP containing aqueous solutions. Using 31P magnetic resonance spectroscopy to measure free magnesium concentration, enzymatic hydrolysis of the artificial membrane vesicles by phospholipase C was shown to reduce the free magnesium concentration. Since activation of phospholipase C has been demonstrated to occur following traumatic brain injury, we propose that this event may initiate decline in free magnesium levels in vivo.