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Ionic Dependence of Membrane Potential and Glutamate Receptor‐Linked Responses in Synaptoneurosomes as Measured with a Cyanine Dye, DiS‐C 2 ‐(5)
Author(s) -
Åkerman Karl E. O.,
Scott Ian G.,
Heikkila Jari E.,
Hein Erkki
Publication year - 1987
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1987.tb04128.x
Subject(s) - membrane potential , kainate receptor , chemistry , biophysics , glutamate receptor , membrane , depolarization , reversal potential , ampa receptor , biochemistry , receptor , biology , patch clamp
Membrane potentials of particles present in a sub‐cellular brain preparation, called synaptoneurosomes, have been monitored by measurement of changes in the absor‐bance of a cyanine dye, DiS‐C 2 ‐5. The membrane potential of the particles seems to be dependent on both Cl − and K + diffusion potentials, as judged from dependence of the ab‐sorbance changes on the K + equilibrium potential across the membrane in the presence of Ba 2+ or when Cl − was replaced with gluconate. The apparent high Cl − permeability of the membrane preparation was reduced in the presence of pic‐rotoxin, a finding suggesting endogenous activation of receptor‐linked Cl − channels. Glutamate and kainate caused depolarization of the membranes present in the preparation. This effect was only seen if K + channels had been blocked in the presence of Ba 2+ or 4‐aminopyridine. No responses were observed with other glutamate receptor agonists (quisqualate or N ‐methyl‐d‐aspartate). The membrane potential of particles present in conventional synaptosomal preparations neither had a high Cl − permeability nor reacted to glutamate or kainate in the present conditions. The results suggest that synaptoneurosome preparations may be used for functional studies on postsynaptic neurotransmit‐ter receptor‐linked membrane potential changes with optical probes of membrane potential.