急性分离大鼠新皮层神经元上激活的K_(ATP)单电导多通道电流

THE ACTIVATED MULTI CHANNEL CURRENTS WITH SINGLE CONDUCTANCE OF K_(ATP) CHANNEL IN ACUTELY DISSOCIATED CEREBRAL NEURONS OF RATS

目的和方法： 探讨脑缺血时ＡＴＰ敏感钾（ＫＡＴＰ） 通道的变化，在急性分离大鼠皮层神经元上，分别采取膜片钳技术的细胞贴附式和内面向外式记录方法，观察ＮａＣＮ、ＡＴＰ、乳酸和ｐＨ 诱发的ＫＡＴＰ，单电导多通道电流。结果：ＫＡＴＰ多通道电流，均为外向电流；第一级电流电导与第二级电流电导基本相同，即为单电导多通道电流。贴附式记录时，对照组和ＮａＣＮ多通道电导分别为（９７ ．１６ ±９ ．３２）ｐＳ和（９３ ．４９ ±７．４４）ｐＳ，后者出现概率（３３．３ ％） 明显高于前者（５．４ ％ ）。膜内面向外式记录时，ＫＡＴＰ多通道电流出现概率，实验组（１ μｍ ｍｏｌ／ＬＡＴＰ４１．７％ ，ｐＨ６ ．０ ４０ ．０ ％ ，３０ ｍｍｏｌ／ＬＬａｃｔａｔｅ ５７ ．４ ％） 明显比对照组（２ ．９ ％） 高（ Ｐ＜０ ．０１）；低浓度ＡＴＰ及ｐＨ 降低诱发的多通道电导与对照组一致，均为２００ ｐＳ 左右；而高浓度乳酸诱发的通道电导为２５０ ｐＳ左右，即高浓度乳酸可增大电导（ Ｐ＜０ ．０１） ；而且高浓度乳酸诱发的单电导多通道电流需用高浓度ＡＴＰ（１０ ｍｍｏｌ／Ｌ） 和Ｇｌｉｂ（０．２ ｍ ｍｏｌ／Ｌ） 方能阻断，说明高浓度乳酸可降低ＫＡＴＰ通道对ＡＴＰ的敏感?

Aim:To study the changes of ATP sensitive potassium channel when ischemia.Methods: We took cell attached and inside out configurations of patch clamp technique and observed the multi channel currents with single conductance of K ATP channel induced by NaCN, ATP, lactate or pH in acutely dissociated cerebral neurons of rats. Results: All currents recorded were outward, its first currents were consistent with the second currents, suggesting that the multi channel were of single conductance. The conductance of K ATP channel recorded with cell attached configuration were 97.16±9.32 pS in control group and 93.49±7.44 pS in NaCN group respectively. The probability (33.3%) recorded in the latter was more than control (5.4%)significantly (P<0.01). With inside out configuration. the probabilities which were 41.7% in ATP (1 μmmol/L) group, 40.0% in pH 6.0 and 57.4% in Lactate(30 mmol/L) were much more than control (2.9%)( P <0.01 ). The conductance in ATP and pH and control group were 200 or so PS. But which in lactate group was about 250 pS, and larger than the others( P <0.01). Moreover, the multi channel currents induced by 30 mmol/L lactate were blocked by 10 mmol/L ATP or 0.2 mmol/L Glib, which indicated that lactate could low ATP sensitivity of K ATP channel. Conclusion:These factors such as extracellular NaCN, intracellular 1 μmmol/L ATP, pH 6.0 and 30 mmol/L lactate may activate K ATP multi channel currents and enhance protective action of K ATP channel from hypoxic and ischemic injury.