top of page

Fixed Potential Amperometry

In Fixed Potential Amperometry the electrode is given a fixed electrical potential. There are substances that oxidize at that electrical potential and generate current. That current is measured. The “in vitro” tests provide information relating concentration with current. This allows measuring concentration in “in vivo” experiments. In this case carbon fiber electrodes and amphetamine (which causes dopamine release) are used. The dopamine, serotonin and noradrenaline oxidize at this electrical potential and they can generate current. The position of the carbon fiber electrode in the brain could tell which neurotransmitter is the most probable to be generating the current. In other type of biosensors specific enzymes are used to restrict the generation of current to a specific neurotransmitter.

In vitro measurement of the biosensor sensibility

In vivo measurement of dopamine levels in the basal ganglia after injection of amphetamine

These biosensors were wirelesss and the recordings used telemetry so some noise and artifacts can be recorded. The data can be exported and noise and artifacts removed. The in vitro test should be done at the end of each experiment

because the current is always reducing. After recordings are done for 5 days, the baseline current levels are lower than during the first days. In the following example there was baseline for 2 days and  1,2 and 4mg/kg amphetamine was injected in the next days. There were some increases in currrent when animals were taken from the animal was to the laboratory from the animal care unit.

After noise and artifacts removed
Current is changed to percentage to compare the doses
Stress caused by not handling the rats can cause unexpected increase of dopamine secretion before amphetamine is injected, as shown by high current levels during light periods (before amphetamine injections) in the laboratory.
These biosensors can be used simultaneously with EEG/EMG recordings to relate neurotransmitter levels to behavior or sleep stages in freely moving rats.
FPA

FPA

Assista agora
bottom of page