Comparison of freeze-blowing and funnel-freezing of rat brain for the measurement of cerebral glucose concentration in vivo.
The efficacy of funnel-freezing of rat brain to inactivate metabolic processes and preserve in vivo tissue glucose concentration was validated by comparing the results obtained by funnel-freezing with those obtained with freeze-blowing of brain. The arterial plasma glucose level was clamped at 9 mM in halothane-anesthetized rats to produce identical glucose levels in brain tissue prior to freeze fixation. In funnel-frozen and freeze-blown brains, tissue glucose concentrations were 2.47 +/- 0.05 and 2.47 +/- 0.06 mumol/g (means +/- SEM), respectively. Lactate levels in funnel-frozen brains were slightly but significantly higher than those in freeze-blown brains, i.e., 1.56 +/- 0.05 mumol/g versus 1.30 +/- 0.05 mumol/g (means +/- SEM; p less than 0.05). Regional analysis in funnel-frozen brains revealed that glucose concentrations in superficial and basal brain areas remained approximately equal at 2.30 +/- 0.1 mumol/g and 2.31 +/- 0.09 mumol/g (means +/- SEM), respectively. Our findings indicate that in the anesthetized rat, funnel-freezing of brain is suitable for the measurement of regional in vivo glucose concentrations.
Mies
G
G
Laboratory of Cerebral Metabolism, National Institute of Mental Health, U.S. Public Health Service, Department of Health and Human Services, Bethesda, Maryland 20892.
Cruz
N
N
Sokoloff
L
L
D000818:Animals; D001921:Brain / Q000378:metabolism*; D005615:Freezing; D005947:Glucose / Q000378:metabolism*; D006652:Histological Techniques; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008297:Male; D009994:Osmolar Concentration; D051381:Rats; D011919:Rats, Inbred Strains
D007773:Lactates; D019344:Lactic Acid; D005947:Glucose