Characteristics of the release of adenosine from slices of rat cerebral cortex.

Abstract

The characteristics of the release of adenosine were examined from slices of rat cerebral cortex after incubation with [3H]adenine or [3H]adenosine. Increasing the K concentration of the extracellular medium to 36 or 54 mM did not evoke any release, but release was observed in the first post-K sample. This occurred whether K was present for 2 or 10 min. Ca-free solutions or verapamil prevented the post-potassium release of 3H. Tetraethylammonium bromide and 4-aminopyridine had no effect. Ouabain (100 .mu.M) induced the release of 3H, and did not prevent an additional increment of release after potassium stimulation. Quabain induced release did not occur in Ca-free or Na-free media, but was increased in low Ca (0.1 mM) medium. The characteristics of adenosine release are unlike those of conventional neurotransmitters. The release is probably associated with the influx of Na+ and Ca2+ through Na channels.