CORRELATIONS BETWEEN CHANGES IN MEMBRANE CAPACITANCE INDUCED BY CHANGES IN IONIC ENVIRONMENT AND THE CONDUCTANCE OF CHANNELS INCORPORATED INTO BILAYER-LIPID MEMBRANES
An. Chanturiya et Hv. Nikoloshina, CORRELATIONS BETWEEN CHANGES IN MEMBRANE CAPACITANCE INDUCED BY CHANGES IN IONIC ENVIRONMENT AND THE CONDUCTANCE OF CHANNELS INCORPORATED INTO BILAYER-LIPID MEMBRANES, The Journal of membrane biology, 137(1), 1994, pp. 71-77
The action of metal polycations and pH on ionic channels produced in b
ilayer lipid membranes (BLM) by three different toxins was studied by
measuring membrane capacitance and channel conductance. Here, we show
that critical concentrations of Cd2+, La3+ or Tb3+ induce complex chan
ges in membrane capacitance. The time course of capacitance changes is
similar to the time course of channel blocking by these ions at low c
oncentration. No changes in BLM capacitance or conductance were observ
ed in the range of pH 5.8-9.0. A pH shift from 7.4 to 3-4 or 11-12 ind
uced large changes in BLM capacitance and channel conductance. For all
studied channel-forming proteins, the initial capacitance increase pr
eceded the conductance decrease caused by addition of polycations or b
y a change in pH. A close relationship between membrane lipid packing
and ion channel protein is suggested.