Correlation of local changes in extracellular oxygen and pH that accompany dopaminergic terminal activity in the rat caudate–putamen
Version of Record online: 9 JAN 2003
Journal of Neurochemistry
Volume 84, Issue 2, pages 373–381, January 2003
How to Cite
Venton, B. J., Michael, D. J. and Wightman, R. M. (2003), Correlation of local changes in extracellular oxygen and pH that accompany dopaminergic terminal activity in the rat caudate–putamen. Journal of Neurochemistry, 84: 373–381. doi: 10.1046/j.1471-4159.2003.01527.x
- Issue online: 9 JAN 2003
- Version of Record online: 9 JAN 2003
- Received August 6, 2002; revised manuscript received October 10, 2002; accepted October 11, 2002.
- cerebral blood flow;
- functional magnetic resonance imaging
Terminal activity causes an increase in local cerebral blood flow that can be quantified by measuring the accompanying increase in tissue oxygen. Alkaline pH changes can also follow neuronal activation. The purpose of these studies was to determine whether these changes in extracellular oxygen and pH correlate. Fast-scan cyclic voltammetry was used to detect changes in dopamine, pH and oxygen levels simultaneously in the caudate–putamen after electrical stimulation of the substantia nigra in anesthetized rats. The biphasic increases in oxygen and pH followed similar time courses, and were delayed a few seconds from the immediate release and uptake of dopamine. The changes following administration of neurotransmitter receptor antagonists as well as agents that modulate blood flow were identical for oxygen and pH. Two distinct mechanisms were identified that give rise to the oxygen and pH changes: blood vessel dilatation caused by nitric oxide synthesis after muscarinic receptor activation and adenosine receptor activation. We conclude that changes in blood flow accompanying terminal activity cause alkaline pH shifts by the rapid removal of carbon dioxide, a component of the extracellular brain buffering system.