BmK AS, an active scorpion polypeptide, enhances [H-3]noradrenaline release from rat hippocampal slices

摘要

Slices of rat hippocampus were preincubated with [H-3]noradrenaline ([H-3]NA) and superfused with a medium containing desipramine (1 mM) to prevent the reuptake of NA. Addition of BmK AS (0.4 mM), a polypeptide activator of skeletal muscle ryanodine receptor isolated from Chinese scorpion Buthus martensi Karsch, to the superfusion medium significantly increased [H-3]NA release. The response curve showed a bell-shaped dose-response relationship (0.05-1 mM) with the maximal response at 0.4 mM. Further experiments showed that the increase of [H-3]NA release was dependent on the presence of extracellular Ca2+, and inhibited completely by tetrodotoxin (0.3 mM) and strongly by omega-conotoxin GVIA (0.1 mM). The results observed in this study suggest that BmK AS may induce noradrenaline release by increasing Naf influx.