Latrotoxin channels. Permeability for divalent cations
Lishko, V.K.; Saĭchenko, E.A.; Storchak, L.G.; Gimmerl'reĭkh, N.G.
Biokhimiia 55(9): 1578-1583
1990
ISSN/ISBN: 0320-9725 PMID: 1706630 Document Number: 355976
The dependence of Ca2+ transport in synaptosomes along the channels formed by .alpha.-latrotoxin on [Ca2+]in and the feasibility of transport along these channels of other bivalent cations were studied. It was found that the concentration dependence of Ca2+ influx is nonlinear and is described by the Michaelis-Menten kinetics (Km = 1.07 .+-. 0.19 mM). Mg2+, Ba2+, Sr2+, Mn2+ and Co2+ competitively inhibited the Ca2+ influx via latrotoxin channels. Studies with the use of the fluorescent Ca2+ probes, Quin-2 and Fura-2, revealed that these cations can also penetrate inside synaptosomes via latrotoxin channels. The bivalent cation influx via latrotoxin channels caused a decrease of the membrane potential of synaptosomes. The similarity of properties of latrotoxin and endogenous Ca2+ channels is discussed.