Journal archive > 2005 > N 4, July-August

The thiazole derivative reduces transmembrane currents via ionic channels formed
by ?-latrotoxin and sea anemone toxin in the bilayer lipid membranes

O. Ya. Shatursky, A. V. Romanenko

It was shown that the thiazole derivative 3-decyloxycarbonylmethyl-4-methyl-5-(2-hydroxyethyl)thiazole chloride (DMHT) (0.1 mM) reversibly reduced the transmembrane current in solutions of 10 mM CaCl2 and 100 mM KCl via ionic channels produced by ?-latrotoxin from black widow spider (?-LT) and sea anemone toxin (RTX) in the bilayer lipid membranes (BLM). Introduction of DMHT from the cis-side of BLM inhibited transmembrane current by 31.6 ± 3% and by 61.8 ± 3% from the trans-side of BLM for ?-LT channels. Application of DMHT to the cis-side BLM decreased the inward current through the RTX channels by 50 ± 5%. Addition of Cd2+ (0.1 mM) to the cis- or trans-side of a membrane after the DMHT induced depression of transmembrane current across the ?-LT channels caused its further decrease by 85 ± 5% that coincides completely with the intensity of Cd2+-inhibition in the control experiments without DMHT. These data suggest that DMHT may exert its inhibitory action on ?-LT channels without considerable influence on the ionogenic groups inside the channel cavity. The comparative analysis of effective radii measured for ?-LT and RTX channels on the cis- (0.9 nm and 0.55 nm, respectively) and the trans-side of BLM (< 0.467 nm for ?-LT) allowed to propose the blocking action of DMHT for ?-LT and RTX channels to result from direct penetration into the channel, achieved due to similar hydrodynamic size of blocking molecules and the size of toxin pores.

Recieved: 2005-01-12

Published at the site: 2005-07-04

The original article in Russian is available for download in PDF format.

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