Chronoamperometry Essay
Chronoamperometry is one of several electrochemical techniques which quantify the oxidation or reduction current of electroactive molecules at an electrode. Oxidation or reduction can be induced by changing the applied voltage at the working electrode. The concentration of the electroactive molecules is proportional to the current produced by their oxidation or reduction, which allows one to determine the concentration of electroactive neurotransmitters and other biological molecules of interest. In the chronoamperometry method, a carbon fiber microelectrode (CFM) and a Ag/AgCl reference electrode are placed in a solution of interest or directly into the brain in order to measure the concentration of biogenic amines such as NE. After initially
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For instance, in a study on extracellular 5-HT clearance in the dorsal hippocampus of rats, researchers employed in vivo chronoamperometry techniques, inserting a Nafion-coated CFM into the DG and CA3 regions of the hippocampus. Inserting 5-HT into the extracellular fluid around these areas resulted in electrochemical signals, which were compared to the signals produced in the presence of 5-HT transporter- and NE transporter-blockers to show that both of these transporters play a role in exogenous 5-HT clearance (Daws, Toney, Gerhardt, & Frazer, 1998). Renner, Pazos and Adams (1992) also effectively used Nafion-coated CFMs as part of their chronoamperometry procedure, in order to detect NE overflow, in the form of electrochemical signals, in the thalamus of rats that were exposed to various drugs and physiological stimulation. In another study, researchers electrically stimulated the LC to induce NE release from the LC to the cerebellar cortex of anesthetized rats, which resulted in an overflow of NE-resembling electroactive species. High-speed chronoamperometry, again with Nafion-coated CFMs, was used to take measurements of this evoked release, and these measurements supported the hypothesis that NE was the primary contributor to the electrically-induced signals (Bickford-Wimer, Pang, Rose,
For instance, in a study on extracellular 5-HT clearance in the dorsal hippocampus of rats, researchers employed in vivo chronoamperometry techniques, inserting a Nafion-coated CFM into the DG and CA3 regions of the hippocampus. Inserting 5-HT into the extracellular fluid around these areas resulted in electrochemical signals, which were compared to the signals produced in the presence of 5-HT transporter- and NE transporter-blockers to show that both of these transporters play a role in exogenous 5-HT clearance (Daws, Toney, Gerhardt, & Frazer, 1998). Renner, Pazos and Adams (1992) also effectively used Nafion-coated CFMs as part of their chronoamperometry procedure, in order to detect NE overflow, in the form of electrochemical signals, in the thalamus of rats that were exposed to various drugs and physiological stimulation. In another study, researchers electrically stimulated the LC to induce NE release from the LC to the cerebellar cortex of anesthetized rats, which resulted in an overflow of NE-resembling electroactive species. High-speed chronoamperometry, again with Nafion-coated CFMs, was used to take measurements of this evoked release, and these measurements supported the hypothesis that NE was the primary contributor to the electrically-induced signals (Bickford-Wimer, Pang, Rose,