McCulloch M W, Papanicolaou M, Rand M J
Br J Pharmacol. 1985 Oct;86(2):455-64. doi: 10.1111/j.1476-5381.1985.tb08915.x.
Both phenoxybenzamine and idazoxan increased the efflux of radioactivity elicited by a train of stimulation (4 pulses at 5 Hz) in vasa deferentia preincubated with [3H]-noradrenaline. Phenoxybenzamine increased the release of radioactivity from vasa stimulated with a single pulse, whereas idazoxan did not. The contractile response in both guinea-pig and rat vasa was biphasic: phenoxybenzamine enhanced the initial twitch component and reduced the second component in guinea-pig vasa stimulated with a single pulse or a train of pulses. Idazoxan enhanced both phases of the response of guinea-pig vasa stimulated with a train of pulses but did not affect the response to stimulation with a single pulse. The effect of phenoxybenzamine in increasing the efflux of radioactivity produced by a single pulse of stimulation was abolished by cocaine, indicating that the increase in efflux was due to blockade of noradrenaline uptake. Contractile responses of guinea-pig vasa stimulated with a single pulse in the presence of cocaine were unaltered by phenoxybenzamine, whereas with a train of stimulation the twitch component was enhanced and the second phase was reduced. The effects of phenoxybenzamine or idazoxan on the efflux of radioactivity from rat vasa portions were qualitatively the same as were observed in whole vasa. The contractile response of the prostatic portion consisted of a rapid twitch with a single pulse of stimulation, but was biphasic with a train of stimulation; the response of the epididymal portion was biphasic with either a single pulse or a train of pulses. These results suggest that there is no inhibitory feedback modulation of noradrenaline release with a single pulse of stimulation in guinea-pig and rat vasa deferentia whereas, with a train of stimulation, there is autoinhibition of noradrenaline release.
在与[3H]-去甲肾上腺素预孵育的输精管中，苯氧苄胺和咪唑克生均增加了由一串刺激（5Hz的4个脉冲）引发的放射性外流。苯氧苄胺增加了单脉冲刺激输精管时放射性的释放，而咪唑克生则没有。豚鼠和大鼠输精管的收缩反应都是双相的：苯氧苄胺增强了豚鼠输精管单脉冲或一串脉冲刺激时的初始抽搐成分，并降低了第二成分。咪唑克生增强了豚鼠输精管一串脉冲刺激时反应的两个阶段，但不影响单脉冲刺激的反应。可卡因消除了苯氧苄胺增加单脉冲刺激产生的放射性外流的作用，表明外流增加是由于去甲肾上腺素摄取的阻断。在可卡因存在下，苯氧苄胺对豚鼠输精管单脉冲刺激的收缩反应没有改变，而在一串刺激时，抽搐成分增强，第二阶段减弱。苯氧苄胺或咪唑克生对大鼠输精管部分放射性外流的影响在性质上与在整个输精管中观察到的相同。前列腺部分的收缩反应在单脉冲刺激时由快速抽搐组成，但在一串刺激时是双相的；附睾部分的反应在单脉冲或一串脉冲时都是双相的。这些结果表明，在豚鼠和大鼠输精管中，单脉冲刺激时去甲肾上腺素释放不存在抑制性反馈调节，而在一串刺激时，存在去甲肾上腺素释放的自身抑制。
