Giniatullin R A
Neirofiziologiia. 1992;24(4):387-95.
The phenomenon of repetitive firing (RG) in motor nerve endings induced by 4-aminopyridine (4-AP) was studied in cut sartorius frog muscle under the voltage clamp conditions. In the presence of 4-AP (1.10(-4) mol/l) one stimulus applied to the nerve induced two end plate currents (EPC) in half of cells studied (n = 35). The elevation of calcium ion concentration up to 5.4 mmol/l or magnesium to 5-9 mmol/l or rhythmic activity (0.05 Hz and above) abolished RF. Substitution of calcium by strontium or barium enhanced RF (the number of EPC during the burst of RF). EPC with very slow time course were observed in some cells in the presence of barium, that disrupted to the burst of RF by repetitive nerve stimulation. Neostigmine, an anticholinesterase agent, increased the number of EPC in the burst of RF, but alpha-bungarotoxin exerted no effect on the RF. The role of calcium and calcium-activated potassium currents in generation and termination of RF in motor nerve endings is discussed.
在电压钳制条件下，对离体的蛙缝匠肌运动神经末梢中由4-氨基吡啶（4-AP）诱发的重复放电（RG）现象进行了研究。在存在4-AP（1×10⁻⁴ mol/l）的情况下，对神经施加一次刺激，在所研究的一半细胞（n = 35）中诱发了两个终板电流（EPC）。将钙离子浓度提高到5.4 mmol/l或镁离子浓度提高到5 - 9 mmol/l，或节律性活动（0.05 Hz及以上）可消除重复放电。用锶或钡替代钙可增强重复放电（重复放电爆发期间的EPC数量）。在存在钡的情况下，一些细胞中观察到时间进程非常缓慢的EPC，通过重复神经刺激可破坏重复放电的爆发。抗胆碱酯酶药物新斯的明增加了重复放电爆发期间的EPC数量，但α-银环蛇毒素对重复放电没有影响。讨论了钙和钙激活钾电流在运动神经末梢重复放电产生和终止中的作用。
