1. 1. Ionic currents through the sodium system of nodes of Ranvier treated with aconitine were measured under voltage clamp conditions in a Ringer solution containing Na+ or an equimolar amount of various test cations. 2. 2. Average shifts in reversal potentials in nodes of Ranvier treated with aconitine with NH4+, Li+, K+, Rb+, Cs+ in place of Na+ in the Ringer solution are 7.6, -6.8, -25.0, -41.0 and -51.5 mV at 13-14°C. At 20-22°C the sequence of shifts is 7.5, -5.5, -13.5, -29.0 and -41.0 mV. For Tl+ the average reversal potential shift is +3 mV at 20-22°C. 3. 3. The slope of the instantaneous current-voltage relation at the reversal potential in nodes treated with aconitine changed with the various cations tested. The ratios are NH4+/Na+/K+/Rb+/Cs+/Li+ = 1.14 : 1.0 : 0.80 : 0.67 : 0.53 : 0.53. 4. 4. Using a three energy barrier model some of the parameters for the aconitine-modified Na+ channels were estimated (Chizmadgev, Yu. A., Khodorov, B.I. and Aityan, S.Kh. (1974) Bioelectrochem. Bioenerg. 1, 301-312).
ASJC Scopus subject areas
- Cell Biology