[3H]Batrachotoxinin A-20-alpha-benzoate binding in synaptosomes from susceptible and kdr-type resistant German cockroaches, Blattella germanica (L.). [English]
1993
Dong K. | Scott J.G. | Weiland G.A.
Synaptosomal binding of [3H]batrachotoxinin A-20-alpha-benzoate ([3H]BTX-B), a potent sodium channel toxin, was measured in kdr-type resistant (Ectiban-R) and susceptible (CSMA) German cockroaches. Previous studies indicated that the Ectiban-R strain was 8.7-fold cross-resistant to batrachotoxin. Scatchard analysis of [3H]BTX-B binding demonstrated that the resistant and susceptible strains have similar binding affinities (K(D) values 230 and 252 nM) and binding site densities (Bmax values, 6.0 and 7.6 pmol/mg protein). Batrachotoxin, aconitine, and veratridine displaced [3H]BTX-B binding in both strains with IC50 values of 1.0-1.2, 18-19, and 73-77 micromolar, respectively. The dihydropyrazole insecticide RH 3421 displaced [3H]BTX-B binding by 13% only at 10 micromolar, the highest concentration examined. The pyrethroid insecticide deltamethrin had no effect on [3H]BTX-B binding in either strain. Our results indicate that the binding of site 2 neurotoxins to cockroach sodium channels is not altered in the kdr-type resistant strain. Possible molecular mechanisms of kdr-type resistance are discussed.
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