The effects of cAMP and cGMP on the high-voltage activated (HVA) Ca2+ channels in the central neurons isolated from the 3rd instar larvae of the cotton bollworm (Helicoverpa armigera ) were studied using the whole-cell patch clamp technique. With barium as current carrier, the currents of Ca2+ channels were recorded by blocking Na+ and K+ currents.Extracellular application of 0. 1 mmol/L forskolin, a stimulator of adenylyl cyclase (AC), had no effect on the peak amplitude of Ba2+ currents. In contrast, 1 mmol/L cGMP in the intracellular solution suppressed the current amplitude significantly and the inhibition was time- and dose-dependent. The results suggest that the activities of HVA Ca2 + channels in the cotton bollworm may not be affected by the elevated cAMP, but can be inhibited by the increased cGMP.%用全细胞膜片钳法研究了cAMP和cGMP对棉铃虫Helicoverpa armigera 3龄幼虫胸腹神经节细胞高电压激活钙通道的调节作用.细胞外液中加入腺苷酸环化酶(AC)激活剂福斯克林(forskolin)0.1 mmol/L,对于Ba2+介导的钙通道电流激活电压、峰电压、峰电流变化以及通道激活和电流达到峰值的时间无影响.电极内液中加入1 mmol/L的cGMP则明显抑制峰电流,且抑制作用呈时间依赖性和浓度依赖性,而对激活电压、峰电压无影响.结果提示,棉铃虫神经细胞高电压激活钙通道的活动可能不受细胞内cAMP水平提高的影响,但被cGMP抑制.
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