Tk. Chen et al., AMPEROMETRIC MONITORING OF STIMULATED CATECHOLAMINE RELEASE FROM RAT PHEOCHROMOCYTOMA (PC12) CELLS AT THE ZEPTOMOLE LEVEL, Analytical chemistry, 66(19), 1994, pp. 3031-3035
Catecholamine release from rat pheochromocytoma (PC12) cells has been
observed at zeptomole levels using dc-amperometric detection with carb
on fiber microelectrodes. Time-resolved individual exocytic events fro
m PC12 cells have been recorded and analyzed with 1.2 ms time resoluti
on. The average area under 1912 current transients from 13 PC12 cells
corresponds to 190 zmol (114 300 molecules per release event). The ave
rage width at half-height of these current transients is 9.3 ms, in ag
reement with the time frame of exocytosis. The detection limit of the
method reported here is as low as 31 zmol. This is the first report of
direct electrochemical observation of quantal release from PC12 cells
. The successful application of this electrochemical scheme to monitor
catecholamines released from small vesicles also suggests that it may
be possible to apply this technique to monitor quantal release from s
ynaptic vesicles.