Abstract
Although glucose is the primary fuel for the brain, alternative substrates are available. Whether or not a substrate is important depends on bulk delivery to and transport into the brain. We examined LD (mM/min·100gm) and CMRL (mM/min·100gm) before, during, and after hemorrhagic hypotenston in 12 ventilated piglets. Cerebral blood flow (CBF, microspheres) and arteriovenous differences of lactic acid were obtained during control (C), after 15 min of hypotension (H), and 10 (R-10) and 90 (R-90) min after rapid reperfusion with whole blood. Mean arterial pressure (mmHg) fell from 89±2 (x̄±SE) to 36±2* during H, and rose to 89±3 and 85±2 at R-10 and R-90, respectively. Arterial lactic acid (La), rose from 1.93±.21 to 7.11±.67* mM during H, increasing further to 9.21±.95* at R-10; by R-90 La fell to 3.41±.69*. CMRL was similar at C, H, and R-90 (.01±.07, .01±.01 and .01±.01, respectively), but rose 10-fold at R-10, .10±.03*. CMRL mirrored LD; i.e., unchanged during C, H, and R-90 (.17±.02, .25±.05 and .25±.06, respectively), but increased 10-fold at R-10 to 1.07±.16*. Changes in LD reflect those of La and CBF (ml/min·100g), the latter falling from 98±8 to 41±8* during H, but increasing to 131±15* at R-10, and decreasing to 83±11 at R-90. Furthermore, CMRL correlated with LD (r=.68, p<.001). The importance of CBF in substrate delivery and uptake in newborns is demonstrated, as well as the role of La as substrate for cerebral metabolism. (* p <.05 vs. control).
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Laptook, A., Porter, A. & Pete'son, J. ROLE OF BLOOD FLOW IN CEREBRAL LACTIC ACID DELIVERY (LD) AND UPTAKE (CMR ). Pediatr Res 18 (Suppl 4), 332 (1984). https://doi.org/10.1203/00006450-198404001-01432
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DOI: https://doi.org/10.1203/00006450-198404001-01432