Electrical stability of erythrocytes in the presence of divalent cations.

Erythrocytes suspended in a medium of low ionic strength lyse under the effect of an exponential electrical pulse. The percentage of haemolysed cells decreases several-fold in the presence of divalent cations. The protective action of the ions studied increases in the following order: Ca++, Mg++, Zn++. It is assumed that divalent ions bind to the negative charges of the lipid and protein molecules and reduce their electrostatic repulsion, which results in stabilization of the membranes.

Pyronin G as a fluorescent probe for quantitative determination of the membrane potential of mitochondria.

Added to mitochondrial suspension, pyronin G changes the intensity of its fluorescence depending on the membrane potential (energy state) of the mitochondria. The mechanism of this effect is studied and a dependence is obtained between the membrane potential and the fluorescence intensity. This permits quantitative determination of the membrane potential by the changes in the fluorescence of the suspension. A method is proposed for measuring the membrane potential of vesicles in the -120 to -220 mV interval.