老龄小鼠心肌细胞膜的钙激活钾通道

21～24月龄的C57BL/6J小鼠左心室乳头肌的单个细胞用酶法分离。用膜片钳(patchclamp)技术的细胞封接(cellattached)方式,步阶式钳制膜电位,在±60mV范围内,记录钙激活钾通道活动。细胞池液(mmol/L)为:KCl 6;NaCl 123;MgCl_2 1.2;NaH_2Po_4 1.2;CaCl_2 2.5,Hepes 1.2;Glueose 5。电极液(mmol/L)除KCl 126外其余同细胞池液,pH值均为7.4。在上述条件下记录到117.5±9.0pS(n=5),182.9±17.0(n=6)和285.1±12.0pS(n=6)三种电导的通道活动。通道活动表现出爆发式开放和长时间开放两种方式。爆发式     

Genistein对大鼠冠状动脉平滑肌细胞BKCa调控机制研究

目的 探讨Genistein对大鼠冠状动脉平滑肌细胞BKCa的调控机制.方法 通过急性酶分离法获取SD大鼠冠状动脉平滑肌细胞,并经由全细胞膜片钳技术分析Genistein对BKCa通道电流的调控机制.结果 电流幅度、通道开放概率、平均开放时间与膜电位相关(P<0.05);有钙外液中行10-5 mol/L Genistein干预后外向电流(+60 mV)为(303.58±70.36)pA,显著高于对照的(173.02±42.68)pA(P<0.05),而无钙外液孵育0.5 h后行Genistein干预后外向电流与对照比较无显著差异(P>0.05);四乙胺+Genistein干预后外向电流(65.32±6.34)pA,显著低于Genistein干预的(303.58±70.36)pA(P<0.05);BAPTA-AM加入后给予Genistein干预,两组外向电流比较无显著差异(P>0.05).结论 大鼠冠状动脉平滑肌细胞BKCa单通道开放概率、电流幅度与膜电位密切相关;Genistein能快速激活BKCa通道,可能与促使内钙释放有关.     

粉防己碱(Tet)对MDCK细胞钙激活钾通道(KCa)的影响

目的MDCK细胞钙激活钾通道(KCa)的鉴定及探讨Tet对该通道的影响.方法内面向外式(inside-out)膜片钳技术.结果 (1)在对称性高钾溶液([K+].[K+]i=140mmolL1/140mmolL-1)中,主要记录到电导为50.475±0.600pS(n=5)的外向通道电流,随电压增加而增加.(2)浴液中钾离子浓度由140mmolL-1改变为45mmolL-1,在0mV记录到内向电流,从+30mv开始记录到记录到外向电流,电导为50.275±0.294pS(n=5).(3)在对称性高钾溶液、膜电位+60mV时.向浴液中加入不同浓度的Ca2+,从10-7molL-1开始,通道活动浓度依赖性增加.(4)对称性高钾溶液、膜电位为+60mV,向浴液中加入Tet,通道活动在1.5×10-5molL-1时最大,在6.0×10-5molL-1时明显受到抑制,几乎为0,洗脱后,部分恢复.结论(1)在MDCK细胞上记录到中电导钙激活钾通道(IKCa),该通道具有电压依赖性和胞内游离Ca2+浓度依赖性,无整流特性.(2)Tet在7.5×10-6molL-1时对MDCK细胞Ka没有显著影响;在1.5×10-5molL-1促进KCa开放,增加钾离子外流;在6.0×10-5molL-1时抑制MDCK细胞Kca开放,减少钾离子外流.     

大鼠背根神经节分离神经元的延时整流的钾离子单通道

运用膜片钳技术对急性分离的大鼠背根神经节神经元细胞上的电压依赖性钾离子通道进行了研究.在细胞贴附式记录模式下,去极化可以激活一个电导为20pS的钾离子单通道电流,分析了其单通道的特性,提出了其动力学的模型.对于了解大鼠背根神经节神经元细胞的电活动机制具有重要的意义.     

顺铂(DDP)对MDCK细胞钙激活钾通道(KCa)的影响

目的探讨顺铂(DDP)对MDCK细胞KCa的影响.方法利用内面向外式(inside-out)膜片钳技术.结果(1)在对称性高钾溶液([K+].[K+]i=140mmolL-1/140mmolL-1)中,主要记录到电导为51.425±0.570pS(n=5)的外向通道电流,随电压增加而增加.(2)浴液中钾离子浓度由140mmolL-1改变为45mmolL-1,在0mV记录到内向电流,从+30mv开始记录到记录到外向电流,电导为50.385±0.307pS(n=5).(3)在对称性高钾溶液、膜电位+60mV时;向浴液中加入不同浓度的Ca2+,从10-7molL-1开始,通道活动浓度依赖性增加.(4)对称性高钾溶液、膜电位为+60mV,向浴液中加入DDP,从1.5×10-5molL-1开始,DDP使通道活性呈现浓度依赖性减少,洗脱后,通道活性部分恢复.结论(1)本实验在MDCK细胞上记录到中电导钙激活钾通道(IKCa),该通道具有电压依赖性和胞内游离Ca2+浓度依赖性,无整流特性.(2)DDP在7.5×10-6molL-1时对KCa没有显著影响;从1.5×10-5molL-1开始使通道活性呈现浓度依赖性减少,减少钾离子外流.     

大鼠下丘脑神经元L-型Ca~(2+)通道特性与Ba~(2+)浓度关系的研究

目的 :研究不同浓度Ba2 + 情况下 ,新生大鼠下丘脑神经元L -型Ca2 + 通道单通道特性。方法 :采用神经元的急性分离技术 ;用膜片钳细胞贴附式记录方式进行研究。结果 :110mmol/LBa2 + 为载流子与 10mmol/LBa2 + 为载流子时 ,单通道活动不同、电导不同 ,分别为 2 8 6pS和 19 1pS ,平均开放概率也明显不同。结论 :L -型Ca2 + 通道单通道电导、平均开放概率、激活与失活等电生理特性存在明显的Ba2 + 浓度依赖性。     

丹参素对猪冠脉平滑肌细胞钙激活钾通道的作用

目的观察丹参素(DS-182)对原代培养猪冠脉平滑肌细胞钙激活钾通道(KCa)的作用,从单个钾通道水平揭示其扩冠机制。方法采用膜片钳单通道电流记录技术。结果①猪冠脉平滑肌细胞KCa的单通道电导值高,为(291.74±4.89)pS;对膜电位变化及细胞内钙离子浓度变化敏感,能被5~20 mmol/L膜内侧四乙基铵(TEA)所阻断。②在细胞贴附式膜片方式下,细胞外应用10~20μmol/L的DS-182对通道具明显的激活效应;而在内面向外式膜片方式下,细胞内应用5~30μmol/L的DS-182对通道均无明显作用。结论DS-182对通道的激活作用是非直接的,需要一系列的胞内过程。     

糖尿病胃轻瘫大鼠胃平滑肌细胞BK_(Ca)通道的变化

目的:探讨糖尿病胃轻瘫(DGP)的发病机制与胃平滑肌细胞大电导钙激活钾通道(BKCa)变化之间的关系。方法:将大鼠分为对照组和糖尿病胃轻瘫模型组。应用木瓜蛋白酶液急性酶分离大鼠胃平滑肌细胞,采用单通道膜片钳技术记录大鼠胃平滑肌细胞BKCa电流,免疫组织化学技术测定BKCa蛋白KCNMA和KCNMB1的表达。结果:大鼠胃平滑肌细胞BKCa电流的开放具有电压依赖性和胞内钙离子浓度依赖性,可被钾离子通道阻滞剂Ib TX阻断;模型组大鼠胃平滑肌细胞BKCa开放概率及开放幅度增加(P0.05),平均开放时间及平均关闭时间减少(P0.01);模型组大鼠胃平滑肌细胞KCNMB1蛋白表达增加(P0.01),KCNMA蛋白表达无明显变化。结论:DGP发病与胃平滑肌细胞BKCaβ1亚基蛋白表达上调及通道功能活动增强有关,β1亚基蛋白可能通过调节BKCa功能活动参与DGP的发生。     

大鼠下丘脑神经元L-型Ca通道特性与Ba浓度关系的研究

目的:研究不同浓度Ba²⁺情况下,新生大鼠下丘脑神经元L-型Ca²⁺通道单通道特性。方法:采用神经元的急性分离技术;用膜片钳细胞贴附式记录方式进行研究。结果:110mmol/LBa²⁺为载流子与10mmol/LBa²⁺为载流子时,单通道活动不同、电导不同,分别为28.6pS和19.1pS,平均开放概率也明显不同。结论:L-型Ca²⁺通道单通道电导、平均开放概率、激活与失活等电生理特性存在明显的Ba²⁺浓度依赖性。     

酸敏感的离子通道研究

组织细胞酸化是机体生理及病理条件下的常见现象.剧烈运动时,骨骼肌无氧糖酵解增强,乳酸积聚.细胞外液pH值降低;组织损伤、缺氧、癫痫、感染等状态下也常伴有细胞外液pH值的降低.机体如何感受细胞外液pH值的变化来进一步调整其活动,一直是此领域研究的难解之谜.     

Development in in vitro toxicology

There are three principal pressures driving the development of in vitro toxicology: (1) the need for more efficient testing systems to cope with the large number of xenobiotics currently being developed; (2) public pressure to reduce animal experimentation; and (3) a need for a better understanding of the mechanisms of toxicity. Within this, in vitro toxicology is focused on local, systemic, and target-organ toxicity. It is becoming increasingly apparent that a step or decision-tree approach using input of a variety of experimental data (physicochemical properties, biokinetics, cytotoxicity) provides the most efficient system for predicting toxicity. Examples of the use of in vitro toxicity systems for prediction of systemic toxicity and target-organ (liver) toxicity are presented.Originally presented at ECCP 93.     

Age-related changes in polyamines in memory-associated brain structures in rats

Polyamines putrescine, spermidine and spermine are positively charged aliphatic amines and have important roles in maintaining normal cellular function, regulating neurotransmitter receptors and modulating learning and memory. Recent evidence suggests a role of putrescine in hippocampal neurogenesis, that is significantly impaired during aging. The present study measured the polyamine levels in memory-related brain structures in 24- (aged), 12- (middle-aged) and 4- (young) month-old rats using liquid chromatography/mass spectrometry and high performance liquid chromatography. In the hippocampus, the putrescine levels were significantly decreased in the CA1 and dentate gyrus, and increased in the CA2/3 with age. Significant age-related increases in the spermidine levels were found in the CA1 and CA2/3. There was no difference between groups in spermine in any sub-regions examined. In the parahippocampal region, increased putrescine level with age was observed in the entorhinal cortex, and age did not alter the spermidine levels. The spermine level was significantly decreased in the perirhinal cortex and increased in the postrhinal cortex with age. In the prefrontal cortex, there was age-related decrease in putrescine, and the spermidine and spermine levels were significantly increased with age. This study, for the first time, demonstrates age-related region-specific changes in polyamines in memory-associated structures, suggesting that polyamine system dysfunction may potentially contribute to aged-related impairments in hippocampal neurogenesis and learning and memory.     

休克过程中肾上腺髓质素变化的研究进展

Adrenomedullin (AM) is a new peptidergic regulator of vascular function. AM serves as a hormone, which has many biological properties, plays an important role in the many pathophysiological processes, especially shock. This review will highlight the structure, biological properties of AM and the relationship between AM and shock.     

Seasonal variations in acute toxoplasmosis in pregnant women in Slovenia

Between December 1999 and December 2004, 40 081 pregnant women were examined for toxoplasmosis with Toxo-IgG, Toxo-IgM enzyme immunoassay. Women with positive results were then retested with the Toxo-IgG avidity assay for recent toxoplasmosis. Recent acute toxoplasmosis in pregnant women was found to be significantly more frequent (p < 0.01) during winter than summer. The incidence of acute toxoplasmosis during winter-spring was also significantly more frequent (p < 0.025) than summer-autumn. This phenomenon should be taken into account when formulating preventive measures for toxoplasmosis, especially for pregnant women.     

Secular change in menarche in women in Madrid

The age at menarche was estimated by recollection in 1617 women between the ages of 18 and 60 in Madrid and a nearby suburb, Pinto. The population of Pinto is working-class and the Madrid group, taken from residential neighbourhoods , belongs to the upper middle class. In both groups we found a diminution in average age at menarche, from 14.04 to 13.02 years in Madrid and from 14.55 to 13.16 years from about 1935 to about 1965 in Pinto. These changes have been more intense in the group which is less well-off economically, where living conditions have varied much more drastically.     

Uteroglobin in the developing rabbit conceptus in vivo and in vitro

Summary Uteroglobin (UGL) was measured in day- 4 to day-10 rabbit conceptuses by a competitive ELISA. Levels in blastocyst fluid, tissues, coverings and in the early fetus were determined separately. The total amount of UGL increased from 18.4 ng to 6.8 g per conceptus. The UGL content of individual day-6 blastocysts was studied in vitro. Culturing was carried out up to 60 h in Ham's F10 medium with polyvinylpyrrolidone as macromolecular component, with and without progesterone, and with progesterone plus estradiol. UGL was determined in the blastocyst fluids, tissues with coverings and in the culture media. After labelling with [³⁵S]-methionine, protein patterns of total blastocysts and of culture media were analysed by two-dimensional gel electrophoresis and fluorography. The morphology of cultured blastocysts was examined by electron microscopy. During 60 h of culture, the blastocysts expanded in diameter by 84%, and released 19% of their initial UGL content into the medium, independent of the hormonal substitution. Neither de novo synthesis, nor degradation of UGL was found: the protein remained unlabelled in fluorography, and its total quantity was not significantly different from that of non-cultured controls. Trophoblast, endoderm and embryoblast cells showed well preserved cell organelles and intercellular junctions, while the morphological differentiation of the germ layer was inhibited.