Early changes in adenosine A1 receptors in cerebral cortex slices submitted to in vitro ischemia

Abstract The effects of brain ischemia on the maximum binding capacity ( B max ) and affinity ( K d ) of A 1 receptors were studied in the rat cerebral cortex, with an in vitro approach. The results were correlated with changes in 3 H-adenosine release, studied under identical experimental conditions. Fifteen minutes of in vitro ‘ischemia’ (hypoxic, glucose-free medium) induced a significant increase in both B max (2398±132 fmol/mg protein, 151% of the control, P K d (2.43±0.12 nM, 161% of the control, P 3 H]-adenosine labeled cerebral cortex slices to 324% of the control was observed. A trend toward normalization was evident 5–15 min after ‘reoxygenation’ (restoring normal medium), but the binding parameters were still altered after 60 min ( B max 2110±82 fmol/mg protein, K d 2.26±0.14 nM, P 1 receptors, possibly due to desensitization, may be a sign of ischemia-induced cellular damage.