Autoradiographic determination of brain pH following middle cerebral artery occlusion in the rat

A method of quantitative autoradiography using 14C-labelled 5,5-dimethyl-2, 4-oxazolidinedione 14C-DMO to evaluate the local changes in brain pH after ischemia is described. In normal control rats the calculated tissue pH values in gray matter were slightly lower than those in white matter, and there was no significant difference in the calculated pH among the various structures in cortical and subcortical gray matter. Four hours after a left middle cerebral artery (MCA) occlusion, marked reductions in 14C-DMO concentrations were demonstrated in the anterior two-thirds of the cerebral cortex and in the lateral part of the caudate nucleus indicating tissue acidosis in these areas. Although several assumptions are required for the calculation of pH in brain tissue, this method would appear very useful in the investigation of the altered metabolic state in ischemic brain.