Ischemia-induced changes in extracellular levels of striatal cyclic GMP: role of nitric oxide

Using microdialysis, we evaluated temporal changes in striatal extracellular cGMP level following ischemia and its relationship to nitric oxide (NO) production. In untreated animals, significant elevation of cGMP was observed during ischemia and during 4 h of recirculation. In animals treated with L-NAME ischemia induced a modest increase in the cGMP level, but this level was significantly lower than that observed in the untreated animals. These results demonstrate first, that the microdialysis technique can be used to detect changes in extracellular cGMP levels during ischemia and second, that ischemia and recirculation induce a rise in cGMP which is diminished by nitric oxide synthase inhibition, suggesting a linkage to NO production.