Abstract: The effects of botanical alkaloids pesticide matrine on inward sodium channel gating properties of the central neurons isolated from the thoracic and abdominal ganglia of the cotton bollworm, Helicoverpa armigera（Hübner）were studied using wholecell patch clamp technique. It was found that matrine inhibited TTXsensitive sodium current (I_na) in a concentration dependent manner. Matrine at 1, 10 and 100 μmol/L decreased peak I_na by （12.49±1.67）%, （18.79±2.16）% and （43.15±8.17）% (n=8, P<0.05), respectively in 5 minutes after matrine was added to the external solution. Matrine shifted up the currentvoltage relation (I-V) curve, without changing the active and peak current potential and the shape of I-V curve. The results demonstrated that matrine could inhibit Ina, which may partially explain the mechanism of its toxicity effects.

Key words: Helicoverpa armigera; sodium channel, matrine, patch clamp