Efflux of taurine from renal brush border membrane vesicles: Is it adaptively regulated?

The uptake of the -amino acid taurine by rat renal brush border membrane vesicles (BBMV) adapts to changes in dietary sulfur amino acid intake. Initial rateV _max upregulates after ingestion of a low methionine and taurine diet (LTD) and downregulates after a high taurine diet (HTD). This is reflected in vivo by hypotaurinuria after a LTD (90% reduction in excretion) and an 18-fold increase in urine taurine after a HTD. This study was performed to determine whether taurine efflux from BBMV is adaptively regulated by external taurine concentration or by diet. Vesicles were preloaded with varying concentrations of radiolabelled and unlabelled taurine and a 150 mM concentration of various salts. Efflux conditions were: taurine and 150 mM salt inside and 150 mM salt outside. The efflux of five concentrations of taurine (10–500 M) was linear over 6 min, reached equilibrium by 21 min, and was dependent upon intravesicular taurine content. The kinetic characteristics of efflux (E) were significantly different from influx (I):K _m=109.8±5.8 (E) versus 23.6±4.2 (I),P<0.001 [time of linearity=360 s (E) vs. 20 s (I)]. Efflux of taurine was dependent on the presence of both sodium and chloride in the system, but neither external taurine content (0,100 M, 1,000 M) nor external -alanine altered initial efflux. Feeding rats a normal diet, LTD, or fasting altered taurine uptake but not efflux. Efflux does not appear to play a role in the adaptive regulation of taurine transport found in all mammalian species.     

牛磺酸防止白内障形成的组织化学研究

目的：研究牛磺酸对晶体氧化损伤的保护作用。方法：将正常兔晶体分为正常条件培养组,Ｆｅｔｏｎ模型组（氧化损伤组）,氧化损伤同时给０．５％和１％牛磺酸保护组体外培养２４ｈ后,检测各组晶体的总抗氧化能力（Ｔ－ＡＯＣ）水平,可溶性蛋白含量,超氧化歧化酶（ＳＯＤ）,过氧化氢酶（ＣＡＴ）及谷胱苷肽过氧化物酶（ＧＳＨ－ＰＸ）活性蛋白含量以及脂质过氧化反应产物丙二醛（ＭＤＡ）含量。结果：和对照组比较,Ｆｅｔｏｎ模     

慢性支气管炎大鼠内皮素和肾上腺髓质素水平的变化及牛磺酸的作用

目的:探讨内皮素(endothelin,ET)和肾上腺髓质素(adrenomedullin,AdM)在慢性支气管炎大鼠血浆、支气管肺泡灌洗液(bronchoalveolarlavagefluid,BALF)和肺组织中含量的变化及牛磺酸的影响。方法:实验分为慢支组、牛磺酸组和对照组,每组6只大鼠。大鼠吸入含10-6(体积分数)二氧化硫的混合空气建立慢性支气管炎模型。放免法测定ET1和AdM含量。结果:血浆、BALF和肺组织ET1含量,慢性支气管炎动物比对照动物分别增加239%、243%和367%(P<0.01),牛磺酸组比慢支组分别降低31.7%、36.7%和62.6%(P值分别小于0.05、0.01和0.01)。血浆、BALF和肺组织AdM含量,慢支组大鼠比正常对照大鼠分别增加40%、100%和138%(P<0.01),牛磺酸组大鼠比慢支组分别减少18.6%、28.5%和29.5%(P值分别小于0.05、0.01和0.01)。结论:慢性支气管炎病程中ET1和AdM可能发挥一定作用;牛磺酸可能通过阻止ET1和AdM调节紊乱的发生发挥保护作用。     

Regulatory volume response of erythrocytes exposed to a gradual and slow decrease in medium osmolality

 A sudden decrease in external medium osmolality (90 mosmol/kg) causes an immediate swelling of trout erythrocytes, followed by a regulatory volume decrease (RVD) due to activation of both a KCl cotransporter and a taurine transport pathway. Here, we determined how trout red cells respond when they are exposed to a gradual and slow decrease in medium osmolality (80 mosmol/kg at a rate of 0.7 mosmol/kg per min). Erythrocytes were unable to regulate their volume efficiently when swollen gradually and it increased continuously throughout the experimental period (120 min). As long as volume was increased slowly by 15–25%, regulatory pathways remained essentially inactivated, erythrocytes losing no significant amount of intracellular osmotically active solutes. Above this swelling threshold, a response was triggered but the quantity of solutes lost via the regulatory pathways was still not sufficient to counterbalance the continuous entry of water due to the slow and gradual decrease in medium tonicity. Received: 18 January 1999 / Received after revision: 10 February 1999 / Accepted: 11 February 1999     

The effect of taurine on motor behaviour,body temperature and monoamine metabolism in rat brain

Summary Taurine, a putative inhibitory neurotransmitter, was injected in various doses intracerebroventricularly to conscious rats via pre-implanted polythene cannulas. The formation of DOPA and 5-hydroxytryptophan (5-HTP) in various brain regions was investigated by measuring the accumulation of these monoamine precursors induced within 30 min by the intraperitoneal injection of 3-hydroxybenzyl hydrazine HCl (NSD 1015, 100 mg/kg), an inhibitor of the aromatic L-amino acid decarboxylase readily penetrating into the brain. DIPA formation, but not 5-HTP formation was significantly enhanced by taurine in dose-related manner in all brain regions studied, indicating an increased synthesis of both dopamine and noradrenaline. Dopamine depletion induced by -methyltyrosine was significantly retarded by taurine, whereas noradrenaline depletion tended to be enhanced. Endogenous levels of dopamine were increased, whereas the following brain constituents were unchanged: tyrosine, tryptophan, noradrenaline, 5-HT and 5-hydroxyindoleacetic acid. In the exoeriments with NSD 1015, a dose-related decrease in rectal temperature and in motility was observed after taurine treatment, as compared to treatment with the decarboxylase inhibotor alone. Systemic parenteral administration of taurine caused no significant changes in brain monoamines, body temperature or behaviour but decreased the heart noradrenaline levels. The data indicate that taurine, which apparently has to be given intracerebroventricularly in order to reach the brain in sufficient amounts, causes inhibition of firing in central dopamine neurons but has the opposite effect on noradrenaline neurons, perhaps also peripherally, whereas 5-HT neurons appear to be unaffected. In addition, taurine appears to interfere with motor behaviour and temperature regulation, possibly via effects on catecholaminergic systems.     

牛磺酸治疗早产儿全静脉营养胆汁淤积的疗效

目的　观察早产儿应用全静脉营养后是否出现胆汁淤积 ,并探讨牛磺酸治疗胆汁淤积的效果。方法　将小于 33周的早产儿分为甲乙两组 ,均行全静脉营养 ,甲组应用牛磺酸治疗 ,乙组未应用牛磺酸治疗 ,并与大于 33周早产儿及足月儿对照 ,入院后第 1、7、14、2 1天采血测定丙氨酸转氨酶、直接胆红素、γ谷氨酰转肽酶。结果　入院后第 14、2 1天甲乙两组直接胆红素、γ谷氨酰转肽酶显著高于大于 33周的早产儿及足月儿 ,各时段甲乙两组 3项指标无显著差异。结论　较长时间全静脉营养可致胆汁淤积 ,牛磺酸对胆汁淤积治疗无明显效果 ,表明全静脉营养导致胆汁淤积原因的复杂性     

牛磺酸对染铅大鼠海马一氧化氮合酶活力的影响

目的　探讨牛磺酸拮抗铅损害学习记忆能力的作用。方法　采用NADPH d组织化学法 ,研究饮用含不同剂量铅 (0 .0 11、0 .110g L)的水和含不同剂量牛磺酸 (5、10g kg)的饲料喂养的大鼠海马一氧化氮合酶 (NOS)阳性神经元数量的变化。结果　 10g kg的牛磺酸饲料能明显增加染铅大鼠海马CA1区和齿状回NOS阳性神经元的数量。低铅水高牛磺酸饲料组NADPH d阳性神经数量在CA1区为 5 1.80± 4 .6 8,在齿状回为 4 7.4 0± 4 .2 0 ,较低铅水普通饲料组的CA1区 (4 1.2 0± 5 .32 )和齿状回 (39.87± 3.81)明显增多 ,差异有显著性 (P <0 .0 5 )。结论　牛磺酸对铅损害学习记忆能力有较明显的拮抗作用。     

牛磺酸治疗高血压病的疗效及对血管内皮细胞功能的影响

目的观察牛磺酸对原发性高血压病(EH)病人的疗效及血管内皮活性物质内皮素1(ET-1)、血栓素A2(TXA2)、一氧化氮(NO)和降钙素基因相关肽(CGRP)的影响。方法56例EH病人用牛磺酸治疗2个月,观察用药前后血中ET-1、NO、CGRP和TXA2的变化。结果牛磺酸治疗EH总有效率为71.4%。牛磺酸治疗后血中NO、CGRP浓度均较治疗前显著升高(P<0.01),血中ET、TXA2浓度显著下降(P<0.01)。结论牛磺酸有较好的降压作用,可明显改善EH病人血管内皮功能。     

牛磺酸对局灶性脑缺血大鼠神经干细胞增殖的影响

目的:研究牛磺酸对成年大鼠脑缺血后缺血侧神经干细胞增殖的影响及治疗缺血性脑损伤的作用机制。方法:采用开颅热凝闭法制作大脑中动脉阻塞(MCAO)模型,随机分为正常组、假手术组、模型组与牛磺酸组,采用腹腔注射每天给予牛磺酸,采用5-溴脱氧尿苷(Brdu)免疫组化法观察脑缺血后3,7,14d与21d4个不同时相Brdu阳性细胞表达的数量。结果:脑缺血后不同时相缺血侧皮质、海马齿状回和纹状体均有Brdu阳性细胞表达,其中7d时各区的阳性细胞数量明显增加,分别为(18.65±4.38)、(25.63±3.58)、(19.46±2.98),具有统计学意义(P<0.05);不同时相牛磺酸组Brdu阳性细胞表达与模型组比较明显增加(P<0.05)。结论:牛磺酸可促进缺血后脑区Brdu阳性细胞数量的增加,提示牛磺酸对治疗脑缺血有重要作用。     

牛磺酸对化疗后S_(180)荷瘤小鼠增效减毒作用的研究

目的研究牛磺酸对环磷酰胺化疗后S180荷瘤小鼠的增效减毒作用。方法取健康昆明小鼠50只,将S180肿瘤细胞种植于小鼠右腋窝皮下,建立移植性肿瘤模型。实验分为五组。腹腔注射给药,每日1次,连续8 d。观察不同剂量牛磺酸(Tau)与环磷酰胺(CTX)联合用药的抑瘤率;脾指数和胸腺指数;检测骨髓有核细胞数和外周血白细胞数;MTT法检测NK细胞杀伤活性和脾淋巴细胞增殖活性。结果与模型组比较,CTX组抑瘤率为56.65%,CTX+Tau低、中、高剂量组小鼠的抑瘤率分别为60.10%,72.41%,86.70%,有统计学意义(P<0.01);与CTX组比较,CTX+Tau各剂量组外周血白细胞数,骨髓有核细胞数,脾指数,胸腺指数,NK细胞活性,淋巴细胞增殖活性增高。尤其是CTX+Tau中、高剂量组作用显著(P<0.05)。结论牛磺酸与环磷酰胺联合用药具有增效减毒作用。