The effect of the myotoxic Lys49 phospholipase A2 from Agkistrodon contortrix laticinctus snake venom on Na/K-ATPase activity of toad bladders

ACLMT is a myotoxic Lys49 phospholipase A₂ isolated from the venom of the snakeAgkistrodon contortrix laticinctus. We have previously shown that ACLMT increases baseline water transport and partially inhibits vasopressin-stimulated water transport across toad bladders due to an increase in cytosolic calcium. However, these evidences provide insufficient insight into the mechanisms involved in the effects of ACLMT on membrane permeability. In an attempt to better understand such mechanisms, the current study aimed to investigate whether the Na⁺/K⁺-ATPase activity of isolated toad bladders can be affected by the ACLMT and the synthetic peptide from its C-terminal region. The toxin significantly decreased the Na⁺/K⁺-ATPase, while the peptide did not alter it. These findings suggest that the effects of ACLMT on membrane permeability may be due to the inhibition of the Na⁺/K⁺-ATPase activity, and that the C-terminal region may not play a relevant role in this effect. This study contributes toward a better understanding of the mechanisms involved in the toxicity of the snake venom Lys49 PLA₂ myotoxins on biological tissues.     

烧伤大鼠肠道组织内Ca2+-ATPase、CGRP含量对胃肠动力功能的影响

目的研究烫伤大鼠早期肠道组织内Ca2+-ATPase、降钙素基因相关肽(calcitonin gene rdatedpeptide,CGRP)的变化,探讨该Ca2+-ATPase、CGRP含量变化与肠道推进功能的关系,进一步阐明烧伤后胃肠功能障碍的发生机制.方法选用清洁大鼠30只,采用30%烫伤大鼠模型,随机分为烫伤组、内毒素组及对照组测定烫伤后1 h大鼠胃肠推进距离及肠道组织中Ca2+-ATPase和CGRP的含量.结果烫伤及内毒素腹腔注射1 h后大鼠肠道碳素墨水推进距离为(53.00±8.88)cm和(91.00±10.22)cm,对照组为(142.00±11.11)cm,两两比较肠道碳素墨水推进距离,烫伤组和内毒素组明显缩短,差异有显著性(P＜0.001).肠道组织内Ca2+-ATPase分别为(263.8±58.30)、(244.4±105.5)和(380.5±116.7)mol/s,烫伤组及内毒素组肠道组织中Ca2+-ATPase与对照组比较,均有不同程度的降低(P＜0.05),CGRP的含量分别为(52.38±39.23)ng/mL,(20.48±23.11)ng/mL及(0.75±1.96)ng/mL,烫伤组及内毒素组肠道组织中CGRP含量均有不同程度的增高,两两比较差异有显著性(P＜0.01,P＜0.05).结论烫伤早期肠道组织CA2+-ATPase活性下降及CGRP含量的增高与肠道动力功能的减弱有着十分密切的关系.     

大鼠AV3V注射血管紧张素Ⅱ对近球小管Na+,K+-ATP酶活性的影响

目的探讨大鼠第三脑室前腹侧区(AV3V)肾素-血管紧张素系统(RAS)对近球小管Na ,K -AT-Pase活性的影响及作用途径.方法用小动物脑立体定位仪在大鼠AV3V埋植钢管供中枢注射,放射免疫法测定血浆血管紧张素Ⅱ(AngⅡ)及血清内源性洋地黄样物质(EDLS)浓度,立体显微镜下手工微分离近球小管,液体闪烁计数器测定标记磷酸Ⅱ的方法检测近球小管Na ,K -ATPase活性.结果①与AV3V注射人工脑脊液(aCSF)的结果比较,AV3V注射AngⅡ后,血浆AngⅡ水平无显著变化,血清EDLS水平显著升高,近球小管Na ,K -AT-Pase活性显著下降.②在AV3V注射沙拉新后,血浆AngⅡ水平无显著变化,血清EDLS水平显著降低,近球小管Na ,K -ATPase活性显著增加.结论AngⅡ作用于AV3V的AngⅡ受体,引起近球小管Na ,K -ATPase活性降低,AngⅡ的这一作用可能与促进EDLS的释放有关.     

龙葵总碱对肿瘤细胞膜钠泵及钙泵活性影响的研究

目的：观察龙葵总碱对S180小鼠及H22小鼠肿瘤细胞膜Na^＋，K^＋-ATPase及Ca^＋＋，Mg^＋＋-ATPase活性的影响。方法：荷瘤小鼠分为治疗组（高剂量、中剂量、低剂量）和对照组（生理盐水组、环磷酰胺组），分别测定各组肿瘤细胞膜的Na^＋，K^＋ ATPase及Ca^＋＋，Mg^＋＋ -ATPase活性。结果：龙葵总碱对S180小鼠及H22小鼠肿瘤细胞膜Na^＋，K^＋ -ATPase及Ca^＋＋，Mg^＋＋ -ATPase活性均有明显的抑制作用，并且其抑制作用呈量效正相关。结论：龙葵总碱这一作用可能是其抗肿瘤作用机理之一。关键词：龙葵总碱肿瘤细胞膜钠泵钙泵     

Normal kidney function and elevated natriuresis in young men born with low birth weight

The aim of our study was to characterize renal function and its relationship to blood pressure in healthy young Caucasian men born with a birth weight under 2,500 g (LBW). Urinary protein patterns, N-acetylglucosamine and γ-glutamyltransferase activities, fractional sodium and potassium excretions, glomerular filtration rate, blood pressure, and erythrocyte Na⁺/K⁺-ATPase activities were determined in 65 subjects, of whom 49 were born with LBW. Signs of glomerular or tubular damage were not detected in the LBW population. However, the blood pressure and the renal sodium excretion were inversely correlated to the subjects’ birth weight and were higher in LBW subjects than in controls. In contrast, the erythrocyte Na⁺/K⁺-ATPase activities were lower in LBW subjects. An inverse correlation was detected between the subjects’ Na⁺/K⁺-ATPase activities and the renal sodium excretion or blood pressure. In summary, our results suggest that: (1) in young LBW Caucasian males signs of early glomerular and tubular impairment are not present; (2) the elevated renal sodium excretion may be a result of higher blood pressure; (3) the alteration of Na⁺/K⁺-ATPase activity might play a role either in the elevation of blood pressure and/or in the enhanced natriuresis of LBW subjects. Received: 29 November 1999 / Revised: 20 March 2000 / Accepted: 22 March 2000     

心肌肌浆网Ca~(2+)-ATP酶研究进展

在正常心肌舒张期,心肌肌浆网Ca2+-ATP酶(SERCA2a)将Ca2+从胞质中摄回肌浆网中,在心肌肥厚、心力衰竭等病理生理过程中有多条信号通路对SERCA2a进行调节,使其活性和表达量下调。通过转基因及药物治疗上调SERCA2a的表达,可能会成为心力衰竭等疾病治疗的新手段。     

柴芩承气汤减轻急性胰腺炎大鼠胰腺钙超载的机制研究

目的：观察柴芩承气汤（Chaiqinchengqi decoction,CQCQD）对急性胰腺炎大鼠胰腺组织肌浆网钙ATP酶（sarcoendoplasmic reticulum Ca2＋-ATPase,SERCA）mRNA表达的影响。方法：30只SD大鼠随机分成正常对照组、模型组及CQCQD组。采用蛙皮素腹腔注射法建立急性胰腺炎大鼠模型。逆转录聚合酶链式反应检测胰腺组织SERCA1和SERCA2 mRNA表达的变化;激光共聚焦显微镜检测腺泡细胞内钙离子浓度,并比较各组大鼠胰腺组织病理变化。结果：SERCA1 mRNA在正常胰腺和急性胰腺炎胰腺腺泡细胞均不表达。模型组与正常对照组比较,腺泡细胞SERCA2 mRNA表达下调,表达率为0.536（P=0.001）;CQCQD组与模型组比较,腺泡细胞SERCA2 mRNA的表达上调,表达率为1.803（P=0.035）。模型组大鼠细胞内钙离子的荧光强度高于正常对照组及CQCQD组（P〈0.05）;CQCQD组大鼠胰腺组织的病理评分低于模型组（P〈0.05）。结论：CQCQD可以通过上调SERCA2 mRNA表达,减缓胰腺细胞内钙超载,减轻胰腺组织的病理改变。     

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