Evidence against major compartmentalization of H+ in ischemic rat brain tissue

Ischemia leads to intracellular acidosis, the severity of which depends on the availability of glucose for production of lactate and H+. It has been suggested that major compartmentalization of H+ occurs, with glial cells becoming much more acidotic than neurons. Since this issue is of crucial importance for the understanding of mechanisms of ischemic brain damage, we induced complete ischemia by decapitation in hypo-, normo- and hyperglycemic awake rats, yielding brain tissue lactate contents varying between 4 and 27 mumol/g. Using phosphorus nuclear magnetic resonance (NMR) we explored whether a splitting of the phosphorus peak occurred as a reflection of compartmentalization. Forebrains were put in NMR tubes and spectra obtained 15 min after decapitation. Since no such splitting was observed, we conclude that major compartmentalization does not occur in ischemia at the degrees of lactic acidosis studied.