NBQX (2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline) did not affect recovery of high energy phosphates and pH in early reperfusion in a rat model of transient forebrain ischemia. Or: an in vivo 31P NMR spectroscopy study

The new non-NMDA (N-methyl-D-aspartate) receptor antagonist NBQX (2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)quinoxaline) has previously been shown to exert a neuroprotective effect in animal models of cerebral ischemia when administered in the post-ischemic phase. In this investigation the effect of NBQX on acidosis and energy recovery in early reperfusion after 10 min of transient forebrain ischemia with the 2-vessel occlusion model in the rat was studied with 31P NMR spectroscopy. In the intervention group the animals received a bolus dose of NBQX 30 mg.kg-1 i.v. at the start of reperfusion. 31P NMR spectroscopy was used to measure intracellular pH, ATP and phosphocreatine continuously in-vivo during, and after, the ischemic event. The recovery of high energy phosphates and pH was followed during 30 min of reperfusion. Pre-ischemic levels of phosphocreatine were reached after approximately 9-10 min in both groups. Although a slight improvement could be seen in the intervention group there was no significant difference in the rate of recovery between the two groups. ATP reached 90% of preischemic levels after about 8 min without significant difference between the two groups. With respect to the recovery of intracellular pH, no difference could be shown. Our results do not contradict previously published results, but suggest that the potential protective effect of NBQX is not mediated through improved recovery of energy metabolism in early reperfusion.