[Steroidal alkaloid batrachotoxin--instrument for studying voltage-regulated sodium channels].

Results of recent studies on the batrachotoxin (BTX) effect on the properties of voltage-operated sodium channels in excitable membranes are summarized in the review. The following problems are considered: allosteric interaction of the BTX receptor with structural entities of the sodium channel responsible for its activation, inactivation, ion selectivity, binding of polypeptide (scorpion and anemone) toxins, local anesthetics and many blocking drugs; relationship between BTX-induced changes in the sodium conductance and intramembrane charge movement; relationship between ion selectivity and effective pK of the selectivity filter acid group of sodium channels modified by BTX or aconitine; effects of BTX on the behaviour and conductance (gamma) of single sodium channels. The problem of the BTX receptor location and possible mechanism of the sodium channel modification by BTX are discussed.