Hypoxia-induced decrease of brain acetylcholine release detected by microdialysis

The in-vivo extracellular release of acetylcholine (ACh) from the striatum of rats was measured by intracerebral microdialysis. The ACh levels were first estimated under normoxic conditions, after which the rats were exposed to either 10% or 5% oxygen for 1 h. The average ACh content was 2.9 pmol/20 min. During hypoxia, the ACh levels were decreased to 62% and 44% of the control value with 10% and 5% oxygen, respectively. The data confirmed the high sensitivity of the striatal cholinergic system to hypoxia. The results are discussed in relation to the hypothesis that disruption of Ca homeostasis may underlie the hypoxia-induced deficits in ACh release.