Patel N B, Xie Z, Young S H, Poo M
J Neurosci Res. 1985;13(1-2):245-56. doi: 10.1002/jnr.490130117.
Monopolar electric current pulses were focally applied through a micropipette to the growth cone of Xenopus embryonic neurons in culture. Application of the current directly in front of the growth cone modulated the rate of growth cone extension: Negative (sink) currents increased the growth rate, while positive (source) currents reduced the growth rate. When the currents were applied in a direction perpendicular to the direction of the neurite growth, both negative and positive currents produced inhibitory effects. Application of a negative focal current at a 45 degree angle with respect to the direction of neurite growth resulted in an oriented growth of the neurite toward the current sink. However, after the growth cone had been attracted to the vicinity of a current sink, further extension of the neurite was inhibited. These current effects occur rapidly after the onset of the current application, and are at least partially reversible within 1 hr after the termination of the current. The magnitude of current density required to induce a growth cone response was found to be in the order of a few pA per micron2. Such current density is close to that which may be generated at the muscle cell surface by the acetylcholine molecules released from the growth cone during the early phase of nerve-muscle contact.
单极电流脉冲通过微吸管聚焦施加到培养的非洲爪蟾胚胎神经元的生长锥上。在生长锥正前方施加电流可调节生长锥的延伸速率：负（汇）电流增加生长速率，而正（源）电流降低生长速率。当电流沿与神经突生长方向垂直的方向施加时，负电流和正电流均产生抑制作用。相对于神经突生长方向以45度角施加负聚焦电流会导致神经突向电流汇方向定向生长。然而，在生长锥被吸引到电流汇附近后，神经突的进一步延伸受到抑制。这些电流效应在施加电流后迅速出现，并且在电流终止后1小时内至少部分可逆。发现诱导生长锥反应所需的电流密度大小约为每平方微米几皮安。这种电流密度接近在神经 - 肌肉接触早期生长锥释放的乙酰胆碱分子在肌肉细胞表面可能产生的电流密度。
