Giotti A, Luzzi S, Spagnesi S, Zilletti L
Br J Pharmacol. 1983 Aug;79(4):855-62. doi: 10.1111/j.1476-5381.1983.tb10529.x.
Homotaurine (3-aminopropane sulphonic acid) did not inhibit the twitch response in guinea-pig ileum longitudinal muscle whilst gamma-aminobutyric acid (GABA) and (-)-baclofen evoked dose-dependent inhibitions. The inhibitory effects of GABA and (-)-baclofen were prevented in the presence of homotaurine 2 X 10(-4) and 10(-3) M. The log dose-effect curves of GABA and (-)-baclofen were shifted in a parallel manner compatible with competitive antagonism. The pA2 of homotaurine with GABA (4.22 +/- 0.05) and (-)-baclofen (4.26 +/- 0.1) were the same. Homotaurine did not antagonize the inhibitory effects of morphine (ED50 4 X 10(-7) M), noradrenaline (ED50 10(-6) M) or ATP (ED50 1.5 X 10(-5) M). The inferior homologue of homotaurine, taurine 10(-3) M, did not modify the inhibitory effects of GABA and (-)-baclofen. Picrotoxin 5 X 10(-5) M antagonized GABAA receptor-mediated contraction but did not affect GABAB receptor-mediated inhibition. At the same concentration the drug did not influence the antagonistic action of homotaurine, thus showing no GABAA receptor-mediated interference. It may be concluded that homotaurine is a competitive antagonist of GABAB mediated effects in the guinea-pig ileum.
高牛磺酸（3-氨基丙烷磺酸）对豚鼠回肠纵肌的抽搐反应无抑制作用，而γ-氨基丁酸（GABA）和（-）-巴氯芬则引起剂量依赖性抑制。在存在2×10⁻⁴和10⁻³M高牛磺酸的情况下，GABA和（-）-巴氯芬的抑制作用被阻断。GABA和（-）-巴氯芬的对数剂量-效应曲线以平行方式移动，符合竞争性拮抗作用。高牛磺酸对GABA（4.22±0.05）和（-）-巴氯芬（4.26±0.1）的pA2相同。高牛磺酸不拮抗吗啡（ED50 4×10⁻⁷M）、去甲肾上腺素（ED50 10⁻⁶M）或ATP（ED50 1.5×10⁻⁵M）的抑制作用。高牛磺酸的同系物低一级的10⁻³M牛磺酸不改变GABA和（-）-巴氯芬的抑制作用。5×10⁻⁵M的荷包牡丹碱拮抗GABAA受体介导的收缩，但不影响GABAB受体介导的抑制作用。在相同浓度下，该药物不影响高牛磺酸的拮抗作用，因此未显示GABAA受体介导的干扰。可以得出结论，高牛磺酸是豚鼠回肠中GABAB介导效应的竞争性拮抗剂。
