高频纳秒脉冲串作用下活体兔肌肉收缩剂量效应研究

Dose Effect of High Frequency Nanosecond Pulse Bursts on Muscle Contraction of Rabbit in Vivo

为探究不同参数高频纳秒脉冲串作用下动物肌肉收缩的剂量效应,研究了不同电场强度（1 kV/cm、4 kV/cm和8 kV/cm）、串内频率（10 kHz、100 kHz和1 MHz）和串内脉冲个数（1个、10个和100个）的10串单极性高频纳秒脉冲串对活体兔肌肉收缩的影响。将不同参数组合的高频纳秒脉冲串通过平板电极施加至新西兰大白兔大腿股二头肌表面皮肤处,采用贴敷于该肌肉表面皮肤上的三轴加速度传感器测得的加速度信号来评估肌肉收缩的强度。对合加速度模值信号的时域和频域分析结果表明,随着脉冲串各参数强度的增加,信号峰值也会增加,但信号频谱分布均相似,主要分布在60 Hz以下。对实验结果进行多元非线性回归分析发现,信号峰值可以表示成3参数的函数关系,进而说明当施加的脉冲串内频率相对较低时,适当增加串内脉冲个数不会引起肌肉收缩强度的大幅增加;然而当施加的脉冲串内频率相对较高时,串内脉冲个数应该尽量减少以尽可能限制肌肉收缩强度。

In order to explore the dose effect of high frequency nanosecond pulse bursts on muscle contraction, we investigated the effect of 10 unipolar high frequency nanosecond pulse bursts with different electric field intensities（1 kV/cm, 4 kV/cm and 8 kV/cm）, intra-burst frequencies（10 kHz, 100 kHz and 1 MHz） and intra-burst number of pulses（1, 10 and 100） on rabbit muscle contraction in vivo. High frequency nanosecond pulse bursts with different parameters were delivered to the surface skin of rabbit thighs biceps through plate electrode, and the intensity of muscle contraction was assessed using the acceleration signal measured by a three-axis acceleration sensor attached on the surface skin of the muscle. The results of time and frequency domain analysis of synthetic acceleration module value signal show that the peak value of the signal increases as the value of any of the three parameters increases, however, the spectral distributions of the signals are similar, mainly distributing below 60 Hz. The multivariate nonlinear regression analysis of the experimental results reveals that the peak value of the signal can be expressed as a function of the three parameters, which indicate that when the frequency of the applied pulse burst is relatively low, appropriate increase in the intra-burst number of pulses will not strengthen muscle contraction too much. However, the intra-burst number of pulses should be minimized to limit strength of muscle contraction as much as possible when the frequency within the applied pulse burst is relatively high.