力竭游泳对红细胞膜MDA含量、Na^＋—K^＋—ATPase和Ca^2＋—ATPase活性的影响

运动性贫血在运动训练中经常发生 ,不仅常发于耐力性运动员中 ,而且在技巧、速度性等项目中也较为常见 ,它严重影响运动员的机能水平和运动成绩。本实验通过对力竭运动大鼠红细胞膜ＭＤＡ含量、Ｎａ Ｋ ＡＴＰａｓｅ和Ｃａ2 ＡＴＰａｓｅ活性的研究 ,旨在探讨运动性贫血的发生机理 ,为预防和治疗运动性贫血提供一定的理论依据。1　材料与方法(1)实验动物与运动方式　实验选用ＳＤ大鼠 2 4只 ,体重为 2 2 0～ 2 5 0ｇ ,由上海实验动物中心提供。大鼠随机分为 4组 ,每组 6只。即 :对照组 (Ｃ) ;运动后即刻组 (ＥＸ1) ;运动后 1ｈ组 (Ｅ…     

K^＋营养对NaCl胁迫下盐地碱蓬生长及叶片液泡膜V—H^＋—ATP和V—H^＋—PPase活性的影响

对溶液培养的盐地碱蓬（Suaeda salsa L.)幼苗进行不同浓度NaCl胁迫并改变培养液中K^ 浓度,以了解K^ 营养对NaCl胁迫下盐地碱蓬幼苗生长及叶片液泡膜V－H^ -ATPase、V－H^ -PPase活性的影响。提高培养液K^ 浓度可明显增加盐胁迫下碱蓬植株的鲜重、干重,促进盐地碱蓬叶片及根部组织K^ 积累。盐地碱蓬叶片液泡膜V－H^ -ATPase至少由A、B、C、D、E及c亚基组成,其表达量在缺K^ 处理（12μmol/L K^ )下随盐胁迫浓度的增加而减小,而在正常K^ （6mmol/L)培养下则随盐胁迫浓度的增加而增加;盐地碱蓬叶片液泡膜V－H^ -PPase分子量为72kD,在缺K^ 和正常K^ 供应情况下,V－H^ -PPase均有较高表达。V－H^ -ATPase及V－H^ -PPase活性变化与其亚基表达量变化基本成正相关。结果表明：K^ 对盐生植物碱蓬的耐盐性有重要作用,盐胁迫下,K^ 可能参与了V－H^ -ATPase和V－H^ -PPase活性调控。     

植物细胞Ca^2＋的微调系统——Ca2＋—ATPase

本文对植物体细胞Ca^2 -ATPase的类型,亚细胞定位,生化特性,分子量差异,基因克隆,酶活性调节剂以及生理功能等方面的研究进展进行综述和讨论。     

胁迫反应中的液泡膜H^＋—ATPase

在简要阐述植物细胞液泡膜上V型H＋-ATPase的基本结构和一般特性的基础上,介绍在胁迫应答中,该酶通过改变分子结构,调节其功能及其在植物细胞信号转导中可能存在的调节机制,以及液泡膜V型H＋-ATPase在植物抗逆生理行为中的重要作用。     

Ca^2＋预处理对热胁迫下辣椒叶肉细胞中Ca^2＋—ATP酶活性的影响

在常温下生长的辣椒（Capsicum annuum L.）叶肉细胞中Ca^2 －ATP酶主要分布于质膜、液泡膜上,叶绿体的基质和基粒片层上也有少量分布;在40℃下热胁迫不同的时间,酶活性逐渐下降,直到叶绿体超微结构解体。同样条件下,经过Ca^2 预处理后,分布在上述细胞器膜或片层上的酶活性大大提高,表明Ca^2 预处理对该活性具有激活作用;Ca^2 预处理对热胁迫下的超微结构的完整性具有一定的保护作用,并且能使Ca^2 －ATP酶在热胁迫下维持较高活性。结果表明,Ca^2 预处理增强辣椒幼苗的抗热性,可能与其稳定细胞膜、从而使Ca^2 －ATP酶在热迫下保护较高活性有一定关系。     

介质Ca^2＋和La^3＋对酿酒酵母生长的影响

采用正交实验研究了外加Ｃａ＾２＋和Ｌａ＾３＋对酿酒酵母生长的影响。结果表明：外加Ｃａ＾２＋和Ｌａ＾３＋对酿酒酵母的生长均有显的影响,都呈现出低浓度对正效应和高浓度时负效应,当Ｃａ＾２＋浓度为１ｍｍｏｌ／Ｌ及Ｌａ＾３＋浓度为１５μｍｏｌ／Ｌ时酿酒酵母生长最好。     

FURTHER STUDIES ON THE K+-DEPENDENT SWELLING OF PRIMATE CEREBRAL CORTEX IN VIVO: THE ENZYMATIC BASIS OF THE K+-DEPENDENT TRANSPORT OF CHLORIDE

Abstract— The swelling of intact, exposed primate cerebral cortex perfused in vioo under, isosmotic conditions was a linear function of the concentration of K⁺ in perfusate over the range 25–117 mM. The K⁺-dependent swelling was manifested throughout the depth of the cerebral cortex studied and was associated with an increased content of chloride in the swollen tissue, despite the constancy of the concentration of external chloride. The swelling of the cerebral cortex was a linear function of the temperature of the perfusate over the range 15–38°C, despite the constancy of the concentration of external K⁺. Moreover, the content of chloride in the swollen cerebral cortex was a linear function of the temperature of the overlying perfusate, despite the constancy of the external concentration of chloride. The changes in the contents of Na⁺ and K⁺ in the swollen cerebral cortex perfused with solutions containing constant concentrations of external Na⁺ and K⁺ but differing in temperature suggested that the fluid of swelling in the tissue was rich in both K⁺ and CI^-, as had been shown previously in vitro. Perfusion of the exposed, intact cerebral cortex in uiuo with K⁺-rich fluids usually involved the reciprocal reduction of the concentrations of Na+ in the perfusate to maintain isotonicity. When comparable reductions in the concentration of external Na⁺ were achieved by replacement with choline (instead of K⁺), swelling of the perfused, exposed cortex was significantly less than that attributed to isotonic, K⁺-rich but Na⁺-poor fluids. These observations suggested that it was the elevated levels of K⁺ rather than lowered concentrations of Na+ that promoted the swelling of the perfused cerebral cortex. The apparent rate of influx of ³⁶Cl from the perfusate into the underlying exposed and intact monkey cerebral cortex in vivo was a linear function of the concentration of K⁺ in perfusate over the range 25–117 mM and conformed to Michaelis-Menten kinetics when plotted according to Lineweaver and Burk. Moreover, the apparent influx of chloride from perfusate into swollen cerebral cortex was a linear function of the percentage swelling of cerebral cortex over the range 6–30 per cent. However, the apparent rate of influx of chloride from perfusate into unswollen cortex was not consistent with the linear correlation already described for swollen cerebral cortex. One reason for this discrepancy was the reduction in the size of the true (inulin) extracellular space associated with the K⁺-dependent swelling of cerebral cortex in vivo. The anatomical locus for this K⁺-dependent swelling of cerebral cortex was an expanded glial compartment, as demonstrated by electron-microscopy. The parenteral administration (50 mg/kg) or local perfusion (5 mM) of acetazolamide inhibited the K⁺-dependent swelling of cerebral cortex in vivo. Moreover, administration of acetazolamide inhibited the K⁺-dependent increase in content of C1- and the K⁺-dependent rate of influx of ³⁶Cl into swollen cerebral cortex. We have discussed the possible enzymatic basis of these K⁺-dependent alterations in content of fluid and chloride and transport of chloride in mammalian cerebral cortex in viuo.     

铜和镉胁迫对海洋青鳉摄食行为的影响

以海洋青鳉(Oryzias melastigma)为试验动物,分析了铜和镉两种重金属离子胁迫对海洋青鳉摄食行为特征的影响,包括摄食响应时间、摄食量、摄食成功率和摄食效率等参数。结果显示,随着Cu2+浓度的升高,开始时,海洋青鳉的摄食量有所升高,当Cu2+浓度达到0.087 mg/L时有最大的摄食量和最短的摄食响应时间。随后,摄食量出现下降,在0.174 mg/L时达到最低。低浓度的Cu2+还能提高海洋青鳉的摄食成功率和摄食效率,而Cu2+的高浓度和长时间暴露则降低海洋青鳉的摄食成功率和摄食效率。Cd2+对海洋青鳉的摄食行为具有明显的抑制效应, Cd2+抑制海洋青鳉摄食的最低可见效应浓度为0.65 mg/L,摄食量、摄食成功率和摄食效率均随着Cd2+浓度的升高而降低。此外,在Cu2+和Cd2+胁迫下,对食物的响应时间有性别差异,雌性显著短于雄性,还存在群体显著短于个体等现象。     

Ｃu^2＋、Zn^2＋诱导稀有Ｊu鲫应激蛋白质的研究

以稀有Ju鲫为材料,研究了应激蛋白质作为生物学指标的敏感性。结果表明,在无可观察效应浓度下,经５d亚慢性胁迫暴露,以Ｃu^2 为胁迫因子,稀有Ju鲫被诱导出约５４KDa的应激蛋白质;以Ｚn^2 为胁迫因子,稀有Ju鲫被诱导出约９４ＫＤa,67KDa和４０ＫＤa的应激蛋白质。应激蛋白质有可能成为一种生物学指标运用于生态风险性早期预警。     

河豚毒素和Cd2+对Zn2+诱发爆发波放电的影响

本文用微电极细胞内电位记录、通道阻断剂和放射性同位素等技术发现,锌离子可诱发爆发波放电(BD),钠通道阻断剂——河豚毒素对BD无效应,而钙通道阻断剂——Ca²⁺则可使BD消失,Cd²⁺可使[⁶⁵Zn²⁺]_i量减少。以上结果说明,Zn²⁺诱发BD的产生机理很可能是Zn²⁺代替Ca²⁺通过钙通道进入胞内引起的。     

EVIDENCE FOR INVOLVEMENT OF Ca2+ IN THE INCORPORATION OF 32Pi INTO THE PHOSPHATIDYLINOSITOL OF RAT DIAPHRAGM

Abstract— Ethyleneglycol-bis (β-aminoethyl ether)-N-N'-tetraacetic acid (EGTA) inhibited the incorporation of ³²P_i into phosphatidylinositol (PI) in rat diaphragm incubated in Ca²⁺-free Krebs-Ringer medium. Only the labelling of the PI was altered, and no effects on the pool size of PI or on the incorporation of ³²P_i into other phospholipids were observed. The effect of EGTA was concentration-dependent and appeared to be related to its Ca^a+-chelating properties; the inhibition of the incorporation of ³²P_i could be completely reversed by the addition of excess Ca²⁺ but not Mg²⁺. The inhibitory effect of the EGTA was progressively enhanced by lengthening the preincubation of the tissue with EGTA, an observation suggesting that chelation of intracellular or membrane-bound Ca²⁺, rather than extracellular Ca²⁺, was involved in the effect. In contrast to its inhibition of the incorporation of ³²P_i EGTA enhanced the incorporation of [³H]inositol into PI, but this effect was accompanied by an appreciable increase in total uptake of [³Hlinositol by the tissue. Our results suggest that the level of intracellular Ca²⁺ plays a role in the regulation of the incorporation of ³²P_i into PI. Addition of unlabelled α-glycerophosphate to the incubation medium of tissues which had been preincubated with 2-deoxy-d -glucose failed to cause a significant diminution in the inhibition by EGTA of the incorporation of ³²P_i into PI. This experiment suggests, but does not prove, that the effect of EGTA was not at the level of incorporation of ³²P_i into α-glycerophosphate.     

EFFECT OF UNILATERAL VISUAL DEPRIVATION AND VISUAL STIMULATION ON THE ACTIVITIES OF ALKALINE PHOSPHATASE, ACID PHOSPHATASE, Na+−K+ ACTIVATED Mg2+ CATALYSED ADENOSINE TRIPHOSPHATASE AND ON THE CONTENT OF SODIUM AND POTASSIUM IONS OF THE OPTIC LOBE OF ADULT PIGEON

—A study was made of the effects of unilateral visual deprivation and stimulation upon the activities of alkaline phosphatase (EC 3.1.3.1), acid phosphatase (EC 3.1.3.2), Na⁺-K⁺ activated Mg²⁺ catalysed ATPase (EC 3.6.1.4) and upon the Na⁺ and K⁺ contents of the optic lobe of adult pigeon (Columba livia). Visual deprivation was achieved by eyelid suturing or by enucleation and maintained for 1–9 weeks. Unilateral visual stimulation was maintained for 75 min following 72 h of darkness. A statistically significant increase in the activity of alkaline phosphatase activity was observed in the optic lobe after unilateral visual deprivation whereas unilateral visual stimulation resulted in the opposite effect. Acid phosphatase activity was found to be unchanged under all experimental conditions. Na⁺-K⁺ ATPase activity was found to increase significantly following unilateral visual stimulation and following eyelid suturing in the corresponding optic lobes; unilateral enucleation resulted in a decrease in the Na⁺-K⁺ ATPase activity. An increase in the enzyme activity was found to be associated with an increase in the level of Na⁺-ion and a decrease in the level of K⁺-ion, and vice versa.     

CHARACTERIZATION OF THE Ca2+-INDUCED PROTEOLYTIC ACTIVATION OF TRYPTOPHAN HYDROXYLASE FROM THE RAT BRAIN STEM

The incubation of the 35,000 g supernatant of a rat brain stem homogenate in the presence of 7.5 mM-CaC1₂ for 10 min at 25°C resulted in a more than 2-fold increase in its tryptophan hydroxylase activity. This activation was irreversible and involved a reduction in the molecular weight of the enzyme, from 220,000 to 160,000. The partially proteolysed tryptophan hydroxylase, in contrast to the native enzyme, could not be activated by trypsin, sodium dodecyl sulphate, phosphatidylserine or phosphorylating conditions; dithiothreitol and Fe²⁺ were the only compounds whose stimulating effect on the enzymatic activity was not prevented by the Ca²⁺ -induced proteolysis of tryptophan hydroxylase. These findings suggest that the mol. wt. 60,000 fragment removed by the Ca²⁺ dependent neutral proteinase plays a critical role in the regulatory properties of tryptophan hydroxylase.     

THE DISTRIBUTION OF AMINO ACIDS, Na+ AND K+ FROM SURFACE TO CENTRE IN INCUBATED SLICES OF MOUSE BRAIN

—The effect of tissue damage on the uptake of amino acids by brain slices was investigated by measuring uptake in slices of different thickness and measuring the distribution of [¹⁴C]-labelled amino acid on the surface and in the centre of incubated slices. The uptake of glutamate, aspartate, and GABA was greater in 0.1 mm-thick slices than in 0.42 mm-thick slices in short and in long (up to 120 min) incubations; the uptake of other amino acids was equal or greater in the 0.42 mm-thick slices. The water content of incubated slices did not change greatly from surface to centre; inulin space was greater at the surface, and in slices from cortex, especially higher at the cut surface. Na⁺ and K⁺ concentrations were also higher at the surface. In the rest of the slice space, inulin, Na⁺ and K⁺ distribution was quite uniform. The distribution of ATP was inhomogeneous: in thinner slices the centre concentration was higher; in thicker slices the centre concentration was lower. Amino acid uptake initially (at 5 min) was higher at the surface, especially in the thicker slices; after longer time (30 min) incubation, the distribution of lysine and leucine was uniform, and glutamate uptake was greater at the surface. The inhomogeneity of distribution increased with increasing thickness of the slices. We concluded that the uptake of some amino acids (perhaps those for which, beside a low affinity transport, also a higher affinity transport system exists) is greater in thinner slices and greater on the surface of slices, and there is an initially inhomogeneous distribution during amino acid uptake. The uptake on the surface constitutes only a small portion of the total uptake, and tissue damage does not explain the greater uptake of amino acids by slices in comparison to the brain in vivo. This shows the higher transport capacity of cells in the brain and emphasizes the importance of mechanisms controlling the metabolite composition of the extracellular fluid in finally influencing the metabolite composition of the brain itself.