Single anion channels reconstituted from cardiac mitoplasts

摘要: Ion channels from sheep cardiac mitoplast (inverted inner mitochondrial membrane vesicle) preparations were incorporated into voltage-clamped planar lipid bilayers. The appearance of anion rather than cation could be promoted by exposing the bilayers to osmotic gradients formed Cl− salts large, relatively imperment, cations at a pH 8.8. Two distinct activities identified. These comprised multisubstate channel intermediate conductance (∼60 pS in 300vs. 50mm choline Cl, ∼100 symmetric 150mm KCl), and lower-conductance (∼25 or ∼50 similar conditions), which only displayed two well-defined substates, ∼25 ∼50% fully open state. larger not simple multiples channels, but both discriminated poorly, extent, between anions (PCl −/Pcholine + ∼12, PCl −/PK +∼8). was minimally selective different (PNO 3 − (1.0)=PCl −>PBr −>PI −>PSCN −(0.8)), its failed saturate even high (>1.0 M) KCl. obviously voltage dependent, they unaffected 0.5 mM SITS, H2O2, propranolol, quinine amitriptyline, 2 ATP, variations (5.5–8.8). Ca2+ Mg2+ did alter single activity, modify current amplitudes channel. This effect, together with voltage-dependent substate behavior, is described following paper.