Acidosis induced by membrane depolarization of neurons: its mechanism and physiological Significance

• Published in: Japanese Journal of Reanimatology Vol. 17; no. 1; pp. 23 - 30
• Main Authors: Zhan, Ren-Zhi, Fujiwara, Naoshi, Taga, Kiichiro, Shimoji, Koki
• Format: Journal Article
• Language: Japanese
• Published: The Japanese Society of Reanimatology 1998; 日本蘇生学会
• Subjects: acidosis; lactate; membrane depolarization; neuronal function; アシドーシス; 乳酸; 神経細胞機能; 膜脱分極
• ISSN: 0288-4348; 1884-748X
• DOI: 10.11414/jjreanimatology1983.17.23

Mechanisms and physiological significance of membrane depolarization-induced cellular pH changes in brain were discussed. The cellular ionic imbalance owing to membrane depolarization activates several pHi regulation mechanisms, including cation/H+ exchangers, HCO3--dependent anion exchangers and H+-pump. These pro-cesses may produce intracellular acidification and extracellular alkalization. Membrane depolarization also accelerates the glycolysis, resulting in lactate accumulation. This lactate accumulation may cause both intracellular and extracellular acidosis in brain tissue. As acidosis decreases some neuronal activities such as excitatory synaptic activity, voltage-dependent Ca2+ conductance and NMDA receptor activity, cellular acidification induced by membrane depolarization may inhibit excessive neuronal excitation and protect neurons from excitotoxic damage. However, severe acidosis produces swelling and injury in neurons and glia. Hence, it is important to characterize the effect of cellular acid-base balance on neuronal functions and viability in various pathological conditions.