Adenosine-homocysteine interactions in controlling cyclic AMP in rat brain cortical slices.

Preincubation of rat brain cortical slices with homocysteine resulted in a reduction of the cyclic AMP response to subsequently added noradrenaline or isoproterenol. There was no effect of homocysteine on the adenosine response, nor of added S-adenosyl homocysteine on any of the responses studied. The results are interpreted in terms of binding of endogenous adenosine by the enzyme S-adenosylhomocysteinase, and provide further evidence for the controlling role of adenosine on cerebral cyclic AMP production.