Does adenosine release taurine in the A1-receptor-rich hippocampus?
OBJECTIVE
To determine whether taurine would be protective in the hippocampus (rich in A1 receptors but devoid of the A2 receptor effector adenylate cyclase, which mediates the release of taurine) by determining whether taurine is released by adenosine in the non-ischemic hippocampus.


METHODS
Microdialysis of probes, inserted stereotactically into the bilateral hippocampi of five nonischemic brains of anesthetized rabbits and combined with high-performance liquid chromatography, was used to evaluate the effects of adenosine on taurine concentration in the interstitial fluid.


RESULTS
Sequential increase of the dialytic artificial cerebrospinal fluid concentration of adenosine (to 1 x 10(-4) M, 5 x 10(-4) M, 1 x 10(-3) M, 5 x 10(-3) M, and 1 x 10(-2) M) linearly and significantly ( P < 0.0001) increased taurine concentration in the interstitial fluid.


CONCLUSIONS
Adenosine delivered by microdialysis into the interstitial fluid of nonischemic rabbit hippocampus induces release of taurine in a dose-dependent manner, suggesting involvement of additional mechanisms besides the already known A2-receptor-induced release. Taurine can be anticipated to have protective effects in the hippocampus as well.
Miyamoto
T A
TA
Research Department, Kokura Memorial Hospital, 1-1 Kifune-cho, Kokurakita-ku, Kitakyshu 802, Japan.
Miyamoto
K J
KJ