Shaw F D, Bicknell R J, Dyball R E
Neuroendocrinology. 1984 Oct;39(4):371-6. doi: 10.1159/000124007.
The physiological significance of the 'bursting' pattern of firing exhibited by activated vasopressin-secreting neurones was investigated by delivering bursts of electrical stimuli to isolated rat neurohypophyses incubated in vitro and by determining vasopressin release. The stimuli were delivered in bursts at three different average frequencies (2.5, 5.0, and 7.5 Hz). For each average frequency, stimuli were delivered at a constant 10 Hz, and the durations of the burst and silence periods were altered, so that the stimulator was switched on for 25, 50 or 75% of the total time. The burst duration varied from 2.5 to 30 s. The vasopressin release generally increased with the average frequency of stimulation, but varied widely for different burst durations. The vasopressin release per stimulus pulse was found to correlate extremely well (r2 = 0.91) with burst durations of up to 20 s, regardless of the average frequency. If it is assumed that complete recovery from the effects of each burst of stimuli took place during the intervening silence periods, it can be shown that vasopressin release per burst increased as the square of burst duration. By analogy with other neurosecretory systems, facilitation of calcium entry during the bursts may be responsible.
通过向体外培养的离体大鼠神经垂体施加电刺激脉冲并测定抗利尿激素释放，研究了激活的抗利尿激素分泌神经元所表现出的“爆发式”放电模式的生理意义。刺激以三种不同的平均频率（2.5、5.0和7.5赫兹）成组施加。对于每种平均频率，刺激以恒定的10赫兹施加，爆发期和静息期的持续时间改变，以使刺激器开启时间占总时间的25%、50%或75%。爆发持续时间从2.5秒到30秒不等。抗利尿激素释放通常随刺激的平均频率增加，但对于不同的爆发持续时间变化很大。发现每个刺激脉冲的抗利尿激素释放与长达20秒的爆发持续时间相关性极佳（r2 = 0.91），与平均频率无关。如果假设在中间的静息期内从每次刺激脉冲的效应中完全恢复，那么可以表明每次爆发的抗利尿激素释放随爆发持续时间的平方增加。与其他神经分泌系统类似，爆发期间钙内流的促进作用可能是原因所在。
