³¹P-NMR evaluation of postischemia renal ATP and pH levels after ATP-MgCl₂ treatment in rabbits

Phosphorus-31 (³¹P) nuclear magnetic resonance (NMR) spectroscopy was used to measure adenosine triphosphate (ATP) concentration and pH in vivo in rabbits subjected to a 40-minute period of unilateral renal ischemia to determine the effect of infusing ATP-magnesium chloride (MgCl₂, 100 μmol/kg) versus saline at the initiation of reperfusion. Data were compared initially by analysis of variance and then analyzed further using a general linear model with covariate adjustment. ATP-MgCl₂-treated animals did not have higher ATP levels during recovery but did have significantly higher renal blood flow (p<0.05), a significantly decreased rate of recovery from acidosis (p <0.05), and significantly higher urinary output (p <0.01) than saline-treated animals during the recovery period. Therefore, treatment with ATP-MgCl₂ improves postischemic functional parameters in this model of moderate injury without functioning as a direct source of ATP or its precursors. These data add support to the emerging concept that intracellular acidosis protects cells from reperfusion injury.