Abstract
The content cyclic adenosine 3',5'-phosphate in guinea pig cerebral cortex slices increases 20-30-fold after a 5-min exposure to a medium containing 0.05 mM adenosine. A similar increase was observed upon exposure to adenine nucleotides. The effect appeared to be specific for adenine ribose monomers. Methylxanthines (0.5 mM) blocked the effect of adenosine, but the blockade could be surmounted by increasing the adenosine concentration. Mutual potentiation of effects was observed when norepinephrine or histamine was added together with adenosine. Nucleotidase activity was observed in slices and homogenates. While this may be related to the mechanism of the adenosine effect, a direct effect of adenosine on adenyl cyclase or cyclic 3',5'-nucleotide phosphodiesterase could not be implicated in homogenates. Changes in the tissue compartmentation of adenine nucleotides probably play a major role in producing the previously observed increase of cyclic adenosine 3',5'-phosphate during electrical stimulation of slices.
ACKNOWLEDGMENTS We thank Mrs. Arleen Maxwell Haley and Mr. Raymond Ryks for their skillful technical assistance. We are grateful to Dr. Y. Fulmer Shealy, Southern Research Institute, Montgomery, Alabama, for kindly supplying us with the carbocyclic analogue of adenosine in which the ring oxygen of the ribose moiety is replaced by a carbon atom.
- Copyright ©, 1970, by Academic Press Inc.
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