[Localization of the binding site for quaternary derivatives of ajmaline in the Na channel of an excitable membrane].
The effects of external or internal application of quaternary derivatives of ajmaline and N-propyl ajmaline (NMA) to the frog nodes of Ranvier were studied by the voltage clamp method. It was established that external application of NMA is much less effective than that of the tertiary amine ajmaline or its quaternary analog N-ethyl ajmaline at comparable concentration. Even at a concentration of 1 mM NMA when applied externally caused only relatively insignificant tonic and use-dependent inhibition of sodium currents. In contrast, internal application of NMA (1 mM) through the cut ends of the fiber led to pronounced use-dependent inhibition of sodium currents. The conclusion is drawn that the binding site for NMA is located in the inner mouth of the Na channels which becomes available for the charged blocker only after opening of the activation gate.
L D
LD
Zaborovskaia
B I
BI
Khodorov
D000404:Ajmaline / Q000031:analogs & derivatives*; D000818:Animals; D001665:Binding Sites; D066298:In Vitro Techniques; D007473:Ion Channels / Q000187:drug effects / Q000378:metabolism*; D011219:Prajmaline / Q000378:metabolism* / Q000494:pharmacology; D011895:Rana ridibunda; D011901:Ranvier's Nodes / Q000187:drug effects / Q000378:metabolism*
D007473:Ion Channels; D000404:Ajmaline; D011219:Prajmaline
O lokalizatsii uchastka sviazyvaniia chetvertichnykh derivatov aĭmalina v Na-kanale vozbudimoĭ membrany.