Ochoa-de la Paz L D, Martínez-Dávila I A, Miledi R, Martínez-Torres A
Departamento de Neurobiología Molecular y Celular, Laboratorio de Neurobiología Molecular y Celular II, Instituto de Neurobiología, Campus Juriquilla-UNAM Boulevard Juriquilla 3001, C.P. 76230 Juriquilla, Qro., Mexico.
Neurosci Res. 2008 Jul;61(3):302-8. doi: 10.1016/j.neures.2008.03.009. Epub 2008 Apr 4.
A study was made of the effects of taurine on GABArho1 receptors expressed in Xenopus oocytes. The EC(50) and reversal potentials for GABA, taurine and glycine currents were 2.3+/-0.4 microM (-25+/-0.9 mV), 5+/-0.8mM (-27+/-0.4 mV) and 7+/-0.5mM (-22+/-0.6 mV), respectively. Co-application of GABA and taurine, revealed a taurine concentration-dependent biphasic-modulation of the receptor: at 0.3-30 microM taurine potentiated the GABA-currents, whereas at 0.3-30 mM the GABA-currents were reduced. In contrast glycine potentiated the GABA-currents at all concentrations tested. TPMPA, a GABA(C) specific receptor antagonist, also blocked effectively and reversibly the taurine and glycine currents. Finally, lanthanum and zinc modulated the currents generated by the three amino acids. Taurine is abundant in the retina and our observations suggest that taurine may play an important role modulating the retinal GABAergic transmission.
对牛磺酸对非洲爪蟾卵母细胞中表达的GABArho1受体的影响进行了研究。GABA、牛磺酸和甘氨酸电流的半数有效浓度（EC(50)）和反转电位分别为2.3±0.4微摩尔（-25±0.9毫伏）、5±0.8毫摩尔（-27±0.4毫伏）和7±0.5毫摩尔（-22±0.6毫伏）。同时应用GABA和牛磺酸，显示出牛磺酸浓度依赖性的受体双相调制：在0.3 - 30微摩尔时，牛磺酸增强GABA电流，而在0.3 - 30毫摩尔时，GABA电流降低。相比之下，在所有测试浓度下，甘氨酸均增强GABA电流。GABA(C)特异性受体拮抗剂TPMPA也能有效且可逆地阻断牛磺酸和甘氨酸电流。最后，镧和锌调节了这三种氨基酸产生的电流。牛磺酸在视网膜中含量丰富，我们的观察结果表明，牛磺酸可能在调节视网膜GABA能传递中起重要作用。
