Neurological research
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Neurological research · Dec 1994
Effects of topical methylene blue on cyclic GMP level, blood flow, and O2 consumption in focal cerebral ischaemia.
We hypothesized that a decrease in cyclic GMP, a second messenger in the glutamate-nitric oxide pathway, would reduce oxygen consumption and improve O2 balance in the ischaemic cerebral cortex. To test this hypothesis, a study was performed in unilateral middle cerebral artery occluded rats which were assigned to either a control or methylene blue (10(-3) M) group. Regional cerebral blood flow was determined using 14C-iodoantipyrine and regional arterial and venous O2 saturations were determined by microspectrophotometry (n = 6). ⋯ The regional cerebral blood flow and O2 consumption in the control group were 50% and 32% lower than those in corresponding contralateral cortex. Topical methylene blue did not alter regional cerebral blood flow and O2 consumption in the ischaemic cortex. Our data showed that cyclic GMP is not a major controller on O2 supply or O2 consumption in the ischaemic brain.