Potassium channels in synaptosomal membrane examined using patch-clamp techniques and reconstituted giant proteoliposomes.
Synaptosomes isolated from the rat cerebral cortex were mixed with sonicated phospholipid vesicles and subjected to freezing-thawing to acquire giant proteoliposomes. Membranes of these giant proteoliposomes could thus be studied using patch-clamp techniques. Single-channel currents were measured with the inside-out patch of the membrane, in KCl solutions. Three different potassium channels were detected and unit conductances were 15.1, 28.6 and 91.0 pS, respectively, in a symmetrical 150 mM KCl solution. All these channels are more permeable to potassium than to sodium ions, the permeability ratio being about 2:1. Tetraethylammonium ions blocked these channels. The gating of these potassium channels is independent of the membrane potential. Presumably, these channels play a role in the resting membrane potential of presynaptic nerve terminals.
Hirashima
N
N
Faculty of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan.
Kirino
Y
Y
D000818:Animals; D002540:Cerebral Cortex / Q000502:physiology*; D004553:Electric Conductivity; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials; D015221:Potassium Channels / Q000502:physiology*; D011510:Proteolipids; D051381:Rats; D012964:Sodium / Q000502:physiology; D013574:Synaptosomes / Q000502:physiology; D013757:Tetraethylammonium Compounds / Q000494:pharmacology
D015221:Potassium Channels; D011510:Proteolipids; D013757:Tetraethylammonium Compounds; C020485:proteoliposomes; D012964:Sodium