CALCIUM-SENSITIVE UNIVALENT CATION CHANNEL FORMED BY LYSOTRIPHOSPHOINOSITIDE IN BILAYER LIPID-MEMBRANES

A calcium sensitive univalent cation channel could be formed by lysotriphosphoinositide on an artificial bilayer membrane made of oxidized cholesterol. The modified membrane was selectively permeable to univalent cations, but was only very sparingly permeable to anions or divalent cations. Selectivity sequence among group IA cations was Rb+ > Cs+ > Na+ > K+ > Li+. The conductance of the membrane was increased up to a value of about 10-2 ohm-1/cm2 with an increase in the concentration of univalent cation, and was drastically depressed by a relatively small increase in the concentration of calcium ion or other divalent cations. The sequence of depressing efficiency among divalent cations was Zn2+ > Cd2+ > Ca2+ > Sr2+ > Mg2+. © 1978.