Buthus Martensii New Type Of Ion Channel Ligands / Tune Preparations Pharmacological Combination Of Pathological Research

In this study, the pharmacological binding properties of a long-chain scorpion toxin, BmK abT, with mammal brain type and insect sodium channels, and that of a short-chain scorpion toxin, martentoxin, with potassium channels on rat brain synaptosomes have been examined using BIAcore. In addition, the effect of BmK venom on glioma cells has been investigated. 1. The binding of BmK abT to mammal brain and insect sodium channels The binding properties of BmK abT, a unique neurotoxin from Chinese scorpion Buthus martensi Karsch, on mammal brain and insect sodium channels were investigated using the BIAcore assay. Results showed that BmK abT could bind to rat brain synaptosomes with an association rate constant of about 2.49 ×106 M-1 s-1 and a dissociation rate constant of about 1.57 ×10-4 s-1, and to Heliothis nerve cord synaptosomes with an association rate constant of about 1.21 ×107 M-1 s-1 and a dissociation rate constant of about 0.99 ×10-3 s-1. The binding of BmK abT to rat brain synaptosomes could be partially inhibited by increasing the membrane potential, but not by BmK AS, BmK IT2 and BmK I. Binding was not modulated by veratridine. In addition, the binding of BmK abT to Heliothis nerve cord synaptosomes was significantly enhanced by increasing the membrane potential and veratridine concentration and was inhibited by BmK IT2, but not by BmK AS or BmK I. The results suggest that BmK abT binds to a distinct receptor site on mammal brain sodium channels and associates with a related site for depressant insect-selective toxins on insect sodium channels. 2. The binding of martentoxin to mammal brain potassium channels Martentoxin is a novel K+-channel-specific peptide purified from the venom of Buthus martensi Karsch. A biosensor binding assay showed a fast association rate and a slow dissociation rate of martentoxin binding on rat brain synaptosomes. The binding of martentoxin on rat brain synaptosomes could be inhibited regularly by ChTX, and gradually by toosendanin in a concentration-dependent manner, but not by either apamin or P03 from Buthus martensi Karsch. The results indicate that...