Electrochemical detection of histamine and 5-hydroxytryptamine at isolated mast cells.
The electrochemical oxidation of histamine has been investigated as an analytical tool. In a physiological buffer, histamine is oxidized at carbon fiber microelectrodes at potentials close to the background in a chemically irreversible process. Cylindrical carbon fiber electrodes were used as amperometric detectors for histamine separated with a reversed-phase capillary column, and detection limits of 240 amol were achieved. Electrodes with beveled tips were used as real-time sensors by monitoring with repetitive cyclic voltammograms at a scan rate of 800 V/s with a 16.7-ms repetition rate, and detection limits of 1.4 microM were achieved. Both techniques were used to probe histamine and 5-hydroxytryptamine (5-HT) stored in rat peritoneal mast cells. The content in single cells was measured by capillary HPLC, and both substances were found in single cells. Although the analysis revealed a large cell-to-cell variation in the amount of histamine and 5-HT, the average amount was 150 and 4 fmol of histamine and 5-HT, respectively. Release of histamine and 5-HT was measured with the electrode placed 1 microm from the cell surface. Release was observed as a series of sharp concentration spikes, consistent with corelease of the two substances from individual vesicles following exocytosis.
Pihel
K
K
Department of Chemistry, University of North Carolina at Chapel Hill 27599-3290, USA.
Hsieh
S
S
Jorgenson
J W
JW
Wightman
R M
RM
D000818:Animals; D002478:Cells, Cultured; D002851:Chromatography, High Pressure Liquid; D004563:Electrochemistry; D005089:Exocytosis; D006632:Histamine / Q000032:analysis* / Q000378:metabolism; D008297:Male; D008407:Mast Cells / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism; D008839:Microelectrodes; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000032:analysis* / Q000378:metabolism
D012701:Serotonin; D006632:Histamine