To study the central effects of adenosine on hypoxia, the influence of treatment by the A, receptor agonist cyclohexyladenosine (1 mu M) or by the antagonist theophylline (10 mu M) was tested on cell damage in a model of neuronal culture. Whereas theophylline enhanced cell injury induced by 8 h hypoxia, cyclohexyladenosine decreased lactate dehydrogenase leakage, abolished the transient increase in 2-D-deoxyglucose transport and improved cell morphology. Such actions might involve regulation of excitatory amino acid release and maintenance of calcium homeostasis.