Astrocytic @entity2227 (Glt) uptake keeps brain interstitial Glt levels low. Within the astrocytes Glt is converted to @entity1160 ( @entity7647 ), which is released and reconverted to Glt in neurons. The Glt- @entity7647 cycle is energy demanding and impaired energy metabolism has been suggested to cause low interstitial @entity7647 /Glt ratios. Using microdialysis (MD) measurements from visually noninjured cortex in 33 neurointensive care @entity1 with @entity510 , we have determined how interstitial Glt and @entity7647 , as a reflection of the Glt- @entity7647 cycle turnover, relate to perturbed energy metabolism. A total of 3703 hourly samples were analyzed. The @entity880 / @entity2388 (L/P) ratios correlated to the @entity7647 /Glt ratios (r=-0.66), but this correlation was not stronger than the correlation between L/P and Glt (r=0.68) or the correlation between lactate and Glt (r=0.65). A novel observation was a linear relationship between interstitial @entity2388 and @entity7647 (r=0.52). There were 13 periods (404 h) of 'energy crisis', defined by L/P ratios above 40. All were associated with high interstitial Glt levels. Periods with L/P ratios above 40 and low @entity2388 levels were associated with decreased interstitial @entity7647 levels, suggesting @entity63 and failing astrocytic @entity7647 synthesis. Periods with L/P ratios above 40 and normal or high @entity2388 levels were associated with increased interstitial @entity7647 levels, which may represent an astrocytic hyperglycolytic response to high interstitial Glt levels. The results imply that moderately elevated L/P ratios cannot always be interpreted as failing energy metabolism and that interstitial @entity2388 levels may discriminate whether or not there is sufficient astrocytic capacity for Glt- @entity7647 cycling in the brain.

Cerebral XXXX and @entity2227 levels in relation to compromised energy metabolism: a microdialysis study in @entity510 @entity1 .

@entity1 :: ('9606', 'Species') :: ['patients'] @entity2227 :: ('CHEBI:29987', 'Chemical') :: ['glutamate'] @entity1160 :: ('CHEBI:28300', 'Chemical') :: ['glutamine'] @entity510 :: ('MESH:D013345', 'Disease') :: ['subarachnoid hemorrhage'] @entity63 :: ('MESH:D007511', 'Disease') :: ['ischemia'] @entity7647 :: ('CHEBI:32668', 'Chemical') :: ['Gln'] @entity880 :: ('MESH:D019344', 'Chemical') :: ['lactate'] @entity2388 :: ('MESH:D019289', 'Chemical') :: ['pyruvate']
@entity1160 :: (CHEBI:28300,Chemical) :: ['glutamine']
