Voltage-dependent chloride conductance of the squid axon membrane and its blockade by some disulfonic stilbene derivatives.
When giant axons of squid, Sepioteuthis, were bathed in a 100 mM Ca-salt solution containing tetrodotoxin (TTX) and internally perfused with a solution of 100 mM tetraethylammonium-salt (TEA-salt) or tetramethylammonium-salt (TMA-salt), the membrane potential was found to become sensitive to anions, especially Cl-. Membrane currents recorded from those axons showed practically no time-dependent properties, but they had a strong voltage-dependent characteristic, i.e., outward rectification. Cl- had a strong effect upon the voltage-dependent membrane currents. The nonlinear property of the currents was almost completely suppressed by some disulfonic stilbene derivatives applied intracellularly, such as 4-acetoamido-4'-isothiocyanostilbene-2,2'-disulfonic acid (SITS) and as 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), which are blockers of chloride transport. On the basis of these experimental results, it is concluded that a voltage-dependent chloride-permeable channel exists in the squid axon membrane. The chloride permeability (PCl) is a function of voltage, and its value at the resting membrane (Em = -60 mV) is calculated, using the Goldman-Hodgkin-Katz equation, to be 3.0 X 10(-7) cm/s.
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D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology*; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D001369:Axons / Q000378:metabolism*; D002712:Chlorides / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology; D049832:Decapodiformes; D007425:Intracellular Membranes / Q000378:metabolism*; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism; D008564:Membrane Potentials / Q000187:drug effects; D010539:Permeability; D000644:Quaternary Ammonium Compounds / Q000494:pharmacology; D013267:Stilbenes / Q000494:pharmacology*; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology
D002712:Chlorides; D007473:Ion Channels; D000644:Quaternary Ammonium Compounds; D013267:Stilbenes; D013757:Tetraethylammonium Compounds; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; D013779:Tetrodotoxin; D019789:Tetraethylammonium; C027917:tetramethylammonium; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid