[Comparative study of the action of procaine and benzocaine on normal and aconitine-modified sodium channels].

Ionic currents of normal and aconitine modified sodium channels of the Ranvier node membrane were measured under voltage clamp conditions. The experiments with local anesthetics in the external Ringer solution have showed that dissociation constant (Kdis) of normal channel-anesthetic complex for procaine is 0.27 + 0.03 mM, and for benzocaine is 0.68 +/- 0.04 mM. With aconitine modified channels, Kdis increases and becomes 1.32 +/- 0.5 mM and 1.52 +/- 0.3 mM for procaine and benzocaine, respectively. It is ascertained that the development of aconitine effect is inhibited by neutral benzocaine to a lesser extent than by procaine. It is shown that the aconitine effect cannot be reversed by a high concentration of anesthetic. Hence, it appears that aconitine and anesthetic receptors do not coincide.