Angus J A, Korner P I, Jackman G P, Bobik A, Kopin I J
Clin Exp Hypertens A. 1984;6(1-2):371-85. doi: 10.3109/10641968409062571.
The relationship between two indices of transmitter release measured simultaneously and the frequency of 4 field pulses (0.125-2 Hz) were obtained from superfused guinea pig right atria after labelling with 3H-noradrenaline. The relationships between 3H-efflux or rate responses and frequency were hyperbolic. Autoinhibitory feedback did not play a role since phentolamine (1 microM) did not alter the 3H-efflux or rate responses to 4 field pulses that gave 50-60% of the maximum rate response. In the presence of neuronal uptake block (desipramine (0.1 microM) phentolamine enhanced 3H-efflux and rate responses to 4 field pulses at all frequencies. In the absence of desipramine prolonged trains of field pulses (8-12 pulses) at low frequency (0.25 Hz) were not sufficient to activate autoinhibitory feedback. At 2 Hz phentolamine enhanced both responses at 12 field pulses. We conclude that in the right atrium autoinhibitory feedback plays little role in the modulation of transmitter release at levels of stimulation that cause 50-60% of maximum tissue response. The presence of neuronal uptake inhibition or high stimulus strengths are necessary to evoke autoinhibitory feedback.
在用3H-去甲肾上腺素标记后，从灌流的豚鼠右心房获得了同时测量的两个递质释放指标与4个场刺激脉冲频率（0.125 - 2Hz）之间的关系。3H-流出或速率反应与频率之间的关系呈双曲线。自抑制反馈不起作用，因为酚妥拉明（1μM）并未改变对能产生最大速率反应50 - 60%的4个场刺激脉冲的3H-流出或速率反应。在存在神经元摄取阻断（地昔帕明（0.1μM））的情况下，酚妥拉明在所有频率下均增强了对4个场刺激脉冲的3H-流出和速率反应。在没有地昔帕明的情况下，低频（0.25Hz）下长时间的场刺激脉冲序列（8 - 12个脉冲）不足以激活自抑制反馈。在2Hz时，酚妥拉明在12个场刺激脉冲时增强了两种反应。我们得出结论，在右心房中自抑制反馈在导致最大组织反应50 - 60%的刺激水平下对递质释放的调节中作用很小。存在神经元摄取抑制或高刺激强度是引发自抑制反馈所必需的。
