Brain Extracellular pH Changes During Alterations in Substrate Supply
The alterations in brain extracellular ionic composition during spreading depression (SD), anoxia, ischemia, and profound hypoglycemia have been clarified to a large extent through the use of double-barrelled liquid ion exchanger (LIX) microelectrodes. Recently, a neutral carrier H+- LIX has become available, permitting examination of the extracellular pH (pHe) changes associated with these events [1, 9]. Construction of pH microelectrodes with this exchanger provide the specific advantages of double-barreled LIX microelectrodes, i. e., small tip diameters (2–4 pm as used in these studies), an immediately adjacent reference electrode, and rapid transient response (90% response in ≤ 2 s). We examined the pHe changes during SD and also the pHe changes during events which are initiated by altered substrate supplies, i. e., cerebral ischemia, terminal anoxia, and profound hypoglycemia (the hypoglycemia experiments are work in progress by W. A. C. Mutch in association with A. R. Gardner-Medwin).
KeywordsDepression Ischemia Lactate Titration Hypoglycemia
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- 3.Astrup J, Heuser D, Lassen NA, Nilsson B, Norberg K, Siesjö BK (1978) Evidence against H+ and K+ as main factors for the control of cerebral blood flow: a microelectrode study. In: Cerebral vascular smooth muscle and its control. Ciba Found Symp 56Google Scholar
- 4.Bureš J, Burešovä O, Kőivänek J (1974) The mechanisms and applications of Leao’s spreading depression of electroencephalographic activity. Academic, LondonGoogle Scholar
- 8.Kraig RP, Nicholson C (1978) Extracellular ionic variations during spreading depression. Neu- roscience 3:1045–1059Google Scholar
- 10.Kőivänek J (1962) Concerning the dynamics of the metabolic changes accompanying cortical spreading depression. Physiol Bohemoslov 11: 383–391Google Scholar
- 11.Mutch WAC, Hansen AJ (1984) Extracellular pH changes during spreading depression and cerebral ischemia: Mechanisms of brain pH regulation. J Cereb Blood Flow Metabol: 17–27Google Scholar
- 13.Siesjö BK (1978) Brain energy metabolism. Wiley, ChichesterGoogle Scholar