Effects of Moderate Hypoxemia and Unilateral Carotid Ligation on Cerebral Glucose Metabolism and Acid-Base Balance in the Rat

Abstract

We used our recently developed method for the simultaneous measurement of the local CMR_glc (LCMR_glc) and composite tissue pH to evaluate the response to unilateral carotid ligation and moderate hypoxia [40.1 ± 4.8 (SD) mm Hg]. The LCMR_glc and tissue pH were measured simultaneously in brain slices using [¹⁴C]2-deoxy-d-glucose and [¹⁴C]5,5-dimethyl-2,4-oxazolidinedione. The ipsilateral LCMR_glc was increased significantly in the caudate-putamen and medial thalamus and was surrounded by a much more extensive zone of acidosis, as shown by significant reductions in the tissue pH, which was affected in parietal cortex, caudate-putamen, lateral septal nucleus, medial geniculate, Ammon's horn, and nucleus reticularis of substantia nigra. In regions with an elevated LCMR_glc and acidosis, anaerobic glycolysis combined with ATP hydrolysis are likely to co-exist. In regions characterized by normal glucose metabolism and acidosis, we hypothesize that a direct effect of hypoxia on the sodium/hydrogen ion antiporter may lead to secondary acidosis. Disturbed acid-base balance during hypoxia may have an adverse effect on cerebral function and cause clinical symptoms.