cAMP和cGMP对棉铃虫神经细胞高电压激活钙通道的调节作用

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。

Modulations by cAMP and cGMP of the high-voltage activated Ca2+ channels in the central neurons of the cotton bollworm, Helicoverpa armigera

The effects of cAMP and cGMP on the high-voltage activated (HVA) Ca~(2+) 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 Ca~(2+) 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 Ba~(2+) 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 Ca~(2+) channels in the cotton bollworm may not be affected by the elevated cAMP, but can be inhibited by the increased cGMP.