Starke K, Weitzell R
J Auton Pharmacol. 1980 Nov;1(1):45-51. doi: 10.1111/j.1474-8673.1980.tb00440.x.
1 The effect of gamma-aminobutyric acid (GABA) on postganglionic sympathetic neurotransmission was studied in strips of the rabbit pulmonary artery. The strips were preincubated with 3H-noradrenaline and then superfused with 3H-amine-free medium. They were stimulated either electrically at 2 Hz, or by 60 mM potassium, or by 1 microM tyramine. 2 GABA (1 - 1000 microM) did not change the basal outflow of tritium, but decreased the electrically evoked overflow as well as the contractile response. GABA 1 microM decreased the evoked overflow by 12%, and GABA 1000 microM, by 42%. The effect of GABA was not changed by yohimbine, propranolol, cocaine, corticosterone, or indomethacin. It was not antagonized by picrotoxin or bicuculline methiodide. GABA 100 microM also slightly reduced the potassium-evoked overflow of tritium but did not change the tyramine-evoked overflow. 3 The results show that, in the pulmonary artery of the rabbit, GABA inhibits the release of noradrenaline. Its effect is independent of alpha- and beta-adrenoreceptors and is not mediated by prostaglandins. The effect may be due to activation of presynaptic receptors which appear to differ from conventional GABA receptors inasmuch as they are insensitive to blockade by either picrotoxin or bicuculline.
1 在兔肺动脉条上研究了γ-氨基丁酸（GABA）对节后交感神经传递的影响。将肺动脉条用3H-去甲肾上腺素预孵育，然后用不含3H-胺的培养基进行灌流。用电刺激（2Hz）、60mM钾或1μM酪胺刺激肺动脉条。
2 GABA（1 - 1000μM）不改变基础氚流出量，但可减少电刺激诱发的溢出以及收缩反应。1μM GABA使诱发的溢出减少12%，1000μM GABA使诱发的溢出减少42%。育亨宾、普萘洛尔、可卡因、皮质酮或吲哚美辛不改变GABA的作用。苦味毒或甲碘化荷包牡丹碱不拮抗GABA的作用。100μM GABA也可轻微减少钾诱发的氚溢出，但不改变酪胺诱发的溢出。
3 结果表明，在兔肺动脉中，GABA抑制去甲肾上腺素的释放。其作用独立于α和β肾上腺素能受体，且不由前列腺素介导。该作用可能是由于突触前受体的激活，这些受体似乎不同于传统的GABA受体，因为它们对苦味毒或甲碘化荷包牡丹碱的阻断不敏感。
