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Kinetics of the release of noradrenaline from micropipettes: interaction between ejecting and retaining currents
Author(s) -
BRADSHAW C. M.,
ROBERTS M. H. T.,
SZABADI E.
Publication year - 1973
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1973.tb08543.x
Subject(s) - pipette , microelectrophoresis , chemistry , biophysics , kinetics , current (fluid) , iontophoresis , electrophoresis , time constant , analytical chemistry (journal) , chromatography , thermodynamics , neuroscience , physics , biology , quantum mechanics , electrical engineering , engineering
Summary1 The role of ejecting and retaining currents in determining the kinetics of the release of [ 14 C]‐noradrenaline (NA) from micropipettes of the type used in microelectrophoresis experiments has been investigated by the liquid scintillation counting technique. 2 In the absence of any electrophoretic current a constant rate of release of NA was established. 3 All retaining currents examined gradually reduced the spontaneous release to zero. Higher retaining currents abolished spontaneous release more quickly. 4 A linear relationship was identified between the rate of electrophoretic release of NA and the intensity of the ejecting current. The mean transport number of NA was found to be 0·17. 5 All retaining currents studied reduced the amount of NA released during a subsequent application of an ejecting current. This was due to a prolongation of the time necessary to establish a steady‐state rate of release. The magnitude of this effect was related to both the intensity and the duration of application of the retaining current. 6 The results are discussed in terms of a theoretical model of ion movements within the tip of the micropipette.