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Changes in extra- and intracellular pH in the brain during and following ischemia in hyperglycemic and in moderately hypoglycemic rats.
J Cereb Blood Flow Metab. 1986 Oct; 6(5):574-83.JC

Abstract

Incomplete forebrain ischemia of 15-min duration was induced in rats made hyperglycemic or moderately hypoglycemic prior to ischemia. Tissue CO2 tension, CO2 content, labile tissue metabolites, and extracellular pH (pHe) were measured, and intracellular pH (pHi) was derived by calculation on the assumption that cerebral intracellular fluids can be lumped into one space. In hypoglycemic animals, mean tissue lactate content increased from 2 to 10 mumol g-1. Tissue CO2 content was virtually unchanged and the CO2 tension increased from approximately 50 to approximately 145 mm Hg. In hyperglycemic animals, tissue lactate content rose to 20 mumol g-1, and the CO2 content decreased by 25%, demonstrating that some CO2 was lost to the blood supplied by the remaining perfusion. Accordingly, tissue CO2 tension did not rise above 200 mm Hg. pHe was reduced in proportion to the amount of lactate accumulated, the values obtained in hypo- and hyperglycemic animals showing relatively little scatter (6.76 +/- 0.03 and 6.25 +/- 0.04, respectively). In hypoglycemic animals the extracellular HCO-3 concentration was virtually unchanged, demonstrating that any influx of lactic acid from the cells must have been accompanied by H+ efflux and/or HCO-3 influx via independent routes. In hyperglycemic animals [HCO-3]e fell by greater than 10 mumol ml-1. In both groups [HCO-3]e was reduced during the first 5 min of recovery. Recovery of pHe was slower in hyper- than in hypoglycemic animals. During ischemia calculated pHi fell to 6.37 +/- 0.04 and 5.95 +/- 0.06 in hypo- and hyperglycemic animals, respectively. Differences in pHi were maintained for the first 15 min of recovery, but in both hypo- and hyperglycemic animals pHi had normalized after 30 min. It is concluded that preischemic hyperglycemia leads to a more pronounced intra- and extracellular acidosis than normo- and hypoglycemia, an acidosis that also resolves more slowly during recirculation.

Authors

No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

3760041

Citation

Smith, M L., et al. "Changes in Extra- and Intracellular pH in the Brain During and Following Ischemia in Hyperglycemic and in Moderately Hypoglycemic Rats." Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism, vol. 6, no. 5, 1986, pp. 574-83.
Smith ML, von Hanwehr R, Siesjö BK. Changes in extra- and intracellular pH in the brain during and following ischemia in hyperglycemic and in moderately hypoglycemic rats. J Cereb Blood Flow Metab. 1986;6(5):574-83.
Smith, M. L., von Hanwehr, R., & Siesjö, B. K. (1986). Changes in extra- and intracellular pH in the brain during and following ischemia in hyperglycemic and in moderately hypoglycemic rats. Journal of Cerebral Blood Flow and Metabolism : Official Journal of the International Society of Cerebral Blood Flow and Metabolism, 6(5), 574-83.
Smith ML, von Hanwehr R, Siesjö BK. Changes in Extra- and Intracellular pH in the Brain During and Following Ischemia in Hyperglycemic and in Moderately Hypoglycemic Rats. J Cereb Blood Flow Metab. 1986;6(5):574-83. PubMed PMID: 3760041.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Changes in extra- and intracellular pH in the brain during and following ischemia in hyperglycemic and in moderately hypoglycemic rats. AU - Smith,M L, AU - von Hanwehr,R, AU - Siesjö,B K, PY - 1986/10/1/pubmed PY - 1986/10/1/medline PY - 1986/10/1/entrez SP - 574 EP - 83 JF - Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism JO - J Cereb Blood Flow Metab VL - 6 IS - 5 N2 - Incomplete forebrain ischemia of 15-min duration was induced in rats made hyperglycemic or moderately hypoglycemic prior to ischemia. Tissue CO2 tension, CO2 content, labile tissue metabolites, and extracellular pH (pHe) were measured, and intracellular pH (pHi) was derived by calculation on the assumption that cerebral intracellular fluids can be lumped into one space. In hypoglycemic animals, mean tissue lactate content increased from 2 to 10 mumol g-1. Tissue CO2 content was virtually unchanged and the CO2 tension increased from approximately 50 to approximately 145 mm Hg. In hyperglycemic animals, tissue lactate content rose to 20 mumol g-1, and the CO2 content decreased by 25%, demonstrating that some CO2 was lost to the blood supplied by the remaining perfusion. Accordingly, tissue CO2 tension did not rise above 200 mm Hg. pHe was reduced in proportion to the amount of lactate accumulated, the values obtained in hypo- and hyperglycemic animals showing relatively little scatter (6.76 +/- 0.03 and 6.25 +/- 0.04, respectively). In hypoglycemic animals the extracellular HCO-3 concentration was virtually unchanged, demonstrating that any influx of lactic acid from the cells must have been accompanied by H+ efflux and/or HCO-3 influx via independent routes. In hyperglycemic animals [HCO-3]e fell by greater than 10 mumol ml-1. In both groups [HCO-3]e was reduced during the first 5 min of recovery. Recovery of pHe was slower in hyper- than in hypoglycemic animals. During ischemia calculated pHi fell to 6.37 +/- 0.04 and 5.95 +/- 0.06 in hypo- and hyperglycemic animals, respectively. Differences in pHi were maintained for the first 15 min of recovery, but in both hypo- and hyperglycemic animals pHi had normalized after 30 min. It is concluded that preischemic hyperglycemia leads to a more pronounced intra- and extracellular acidosis than normo- and hypoglycemia, an acidosis that also resolves more slowly during recirculation. SN - 0271-678X UR - https://www.unboundmedicine.com/medline/citation/3760041/Changes_in_extra__and_intracellular_pH_in_the_brain_during_and_following_ischemia_in_hyperglycemic_and_in_moderately_hypoglycemic_rats_ DB - PRIME DP - Unbound Medicine ER -