We
are characterizing the electrochemistry of
adenosine at carbon-fiber microelectrodes.
While dopamine has been extensively studied using carbon-fiber
microelectrodes, the technique has not been widely applied to many of
other
neurochemicals. Adenosine is a
neuromodulator in the brain that has a variety of actions including
regulation
of cerebral blood flow, modulation of neurotransmission, and protection
against
neuronal injury during stroke. No
reliable method currently exists for electrochemical detection of
adenosine in vivo. Direct detection of adenosine using cyclic
voltammetry at carbon-fiber
microelectrodes is being examined. Simultaneous detection of
adenosine and dopamine is possible so interactions can be
monitored. This method
is being used to characterize the mechanisms of adenosine formation in
brain slices and to detect spontaneous transient adenosine release in
anesthetized rats.
In vivo studies of the effects of adenosine. Dopamine, pH, and oxygen changes were measured before (left) and after (right) administration of theophylline, an adenosine receptor antagonist. Applied voltage is the y-axis, elapsed time the x-axis and measured current is in color. The top traces, taken from the color plots, show concentration changes over time. Adenosine receptor antagonism reduces the second peak of oxygen changes.
Pathways
of
adenosine formation. Adenosine can be
formed intracellulary and then transported out of the neuron or
extracellulary
after the breakdown of released
ATP.
