Anion channels from rat brain synaptosomal membranes incorporated into planar bilayers.
Synaptic membranes from rat brain were incorporated into planar lipid bilayers, and the characteristics of two types of anion-selective channels (type I and type II) were investigated. In asymmetric BaCl2 buffers (cis, 100 mM/trans, 25 mM), single channel conductances at -40 mV were 70 pS (type I) and 120 pS (type II). Permeability ratios (PNa:PBa:PCl) calculated from the Goldman-Hodgkin-Katz current equation for type I and type II channels were 0.23:0.04:1 and 0.05:0.03:1, respectively. Both channels exhibited characteristic voltage-dependent bursting activities. Open probability for type I channels had a maximum of approximately 0.7 at about 0 mV and decreased to zero at greater transmembrane potentials of either polarity. Type II channels were relatively voltage independent at negative voltages and were inactivated at highly positive voltages. Type I channels showed spontaneous irreversible inactivation often preceded by sudden transition to subconducting states. DIDS blocked type I channels only from the cis side, while it blocked type II channels from either side.
Nomura
K
K
Department of Pediatrics, Nagoya University School of Medicine, Japan.
Sokabe
M
M
D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000818:Animals; D001464:Barium / Q000378:metabolism; D017609:Barium Compounds; D002462:Cell Membrane / Q000378:metabolism / Q000502:physiology / Q000648:ultrastructure; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D002712:Chlorides; D004553:Electric Conductivity / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D005260:Female; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D008051:Lipid Bilayers / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride / Q000378:metabolism; D013574:Synaptosomes / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure
D017609:Barium Compounds; D002712:Chlorides; D007473:Ion Channels; D008051:Lipid Bilayers; C024986:barium chloride; D001464:Barium; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D012965:Sodium Chloride; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid