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目的 用影响突触前细胞外钙内流及或细胞内钙储池释放钙的措施,研究大、小微抑制性突触后电流(mIPSCs)的一些特性。方法 采用盲法电压钳全细胞记录技术。结果 ①无钙液中加或不加EGTA(200mmol/L)灌流时,均可逆地使大mIPSCs较正常含钙液灌流时明显增多,小mIPSCs的平均频率明显下降;增加细胞外液钙(4mmol/L)浓度,小mIPSCs的频率增加,大mIPSCs变化不明显。Cd2+ (100μmol/L),仅轻度降低小mIPSCs平均频率至对照组的(87. 3±30. 0)% (n=13)。②carbachol(100μmol/L)使小mIPSCs增加至对照组的315. 63%。然而,无钙液中加carbachol,小mIPSCs不增加。含钙液和无钙液中加carbachol均可使大mIPSCs的比例增加。③Thapsigargin(8μmol/L)可使小mIPSCs的平均频率增加至对照组的(132. 1±27. 4)%。④U73122 (40μmol/L)可使小mIPSCs的平均频率降低至对照组的(74. 7±29. 6)%。⑤Procaine(2mmol/L)及咖啡因(10mmol/L)均可降低小mIPSC的平均频率。较高浓度的兰尼定(30 50μmol/L)也降低小mIPSCs的频率。结论 改变灌流液的钙浓度,小mIPSCs的频率受到明显影响。大mIPSCs的出现或增加主要与钙储池释放Ca2+的机制有关。
Objective To investigate some characteristics of mIPSCs in large and small microvessels by means of influencing the extracellular calcium influx in presynaptic cells and calcium release from intracellular calcium pools. Methods Blind voltage clamp whole cell recording technology. Results ① In the absence or presence of EGTA (200mmol / L), calcium infusion significantly reverses the increase of large mIPSCs compared with that of normal calcium-containing solution. The average frequency of small mIPSCs is significantly decreased. Extracellular calcium (4mmol / L) concentration, the frequency of small mIPSCs increased, large mIPSCs did not change significantly. Cd2 + (100μmol / L), only slightly decreased the average frequency of small mIPSCs to (87.3 ± 30.0)% (n = 13) in the control group. Carbachol (100μmol / L) increased the number of small mIPSCs to 315. 63% of the control group. However, no carbachol plus carbachol, small mIPSCs did not increase. The addition of carbachol in both calcium and calcium-free fluids increased the proportion of large mIPSCs. ③ Thapsigargin (8μmol / L) can increase the average frequency of small mIPSCs to (132.1 ± 27.4)% of the control group. ④U73122 (40μmol / L) can reduce the average frequency of small mIPSCs to the control group (74.7 ± 29.6)%. ⑤Procaine (2mmol / L) and caffeine (10mmol / L) can reduce the average small mIPSC frequency. Higher concentrations of ranitidine (30 50 μmol / L) also reduced the frequency of small mIPSCs. Conclusion Changing the concentration of calcium in perfusate, the frequency of small mIPSCs was significantly affected. The appearance or increase of large mIPSCs is mainly related to the mechanism of Ca2 + release from calcium reservoirs.