中华绒螯蟹眼柄神经内分泌细胞表达ATP敏感钾通道

KATP channels expressed in the neurosecretory cells of MTXO in the eyestalks of Eriocheir sinensis

采用膜片钳技术之内面向外记录模式观察了中华绒螯蟹（河蟹）眼柄视神经节端髓X器官（MTXO）神经内分泌细胞对0-1 mmol/L ATP的反应，发现河蟹眼柄MTXO细胞表达ATP敏感钾通道（KATP）。电生理特征研究结果表明，在细胞膜内外两侧的Ｋ＋浓度均为200 mmol/L时，KATP呈弱的内向整流性，电导为68 pS，有翻转电位。灌流ATP对KATP通道的开放产生浓度依赖性抑制作用，当细胞外液中ATP浓度超过0.1 mmol/L后，去极化刺激不能诱发KATP电流，并且1 mmol/L ATP可明显阻断KATP开放活动。胆固醇等甾醇类物质对河蟹眼柄MTXO细胞KATP无明显的影响，但0.1 mmol/L优降糖可完全阻断KATP的单通道开放。KATP受内源性ATP的调控，在细胞代谢与兴奋性耦联中起重要作用，提示河蟹眼柄MTXO细胞的代谢活动对神经多肽激素的分泌产生了反馈调节作用，胆固醇等甾醇类物质未通过调节KATP的活动调控细胞的分泌活动。结果为阐明甲壳动物眼柄神经多肽激素分泌的调控机制提供了新认识。

Sensitivity to 0-1 mmol/L ATP of KATP channel in the neurosecretory cells of MTXO in the eyestalks of Eriocheir sinensis was observed with insideout patchclamp method and properties of KATP channels were studied with selective blocker and steroids. With symmetrical 200 mmol/L K＋ on both sides of the excised membrane, the singlechannel conductance was approximately 68 pS and the reversal potential was observed. These channels had a weak inward rectifying property. ATP applied inhibited channel activity in a concentrationdependent manner. The KATP currents can’t be reduced by depolarized stimulation when concentration of ATP is greater than 0.1 mmol/L. Moreover, opening activity of KATP was blocked when 1 mmol/L ATP was applied. The KATP channels were not obviously affected by cholesterol, but they were completely blocked by 0.1 mmol/L glybenclamide. The adenosine triphosphatesensitive potassium channel, termed KATP channel, is characterized by a strong inhibition of channel activity by intracellular ATP thereby coupling the metabolic state of cells to their excitability and regulating a variety of functions. These results indicate that metabolic state of MTXO has feedback regulation on the secretion of neuropeptides hormone. Cholesterol can’t control secretion of eyestalks hormone by affecting KATP channels.