Freschi J E
Department of Neurology, School of Medicine, Emory University, Atlanta, GA 30322.
Neurosci Lett. 1989 Nov 20;106(1-2):105-11. doi: 10.1016/0304-3940(89)90210-3.
The two-electrode voltage-clamp technique was used to study the ionic basis of the slow depolarization caused by the neuropeptide proctolin. At negative membrane potentials, proctolin caused a dose-dependent slow inward current. This current reversed and became outward at membrane potentials positive to 0 to +20 mV. Current-voltage curves also showed the response to be voltage-dependent, with a reversal potential at positive membrane potentials. The response was blocked in sodium-free solutions. Solutions with reduced sodium concentration caused a shift of the reversal potential in a manner expected for a response that is largely sodium-dependent. We conclude that proctolin causes an inward current by increasing a voltage-dependent cation conductance that is predominantly permeable to sodium.
采用双电极电压钳技术研究神经肽促肠动素引起的缓慢去极化的离子基础。在负膜电位时，促肠动素引起剂量依赖性的缓慢内向电流。该电流在膜电位正向至0至+20 mV时反转并变为外向。电流-电压曲线也显示该反应依赖于电压，在正膜电位时有一个反转电位。在无钠溶液中该反应被阻断。钠浓度降低的溶液导致反转电位的偏移，其方式符合主要依赖于钠的反应的预期。我们得出结论，促肠动素通过增加主要对钠通透的电压依赖性阳离子电导来引起内向电流。
