茶皂苷减轻心肌缺血再灌注损伤的实验研究

目的观察茶皂苷对心肌缺血再灌注(MIR)损伤的保护作用并探讨其机制,为茶皂苷防治心肌缺血再灌注损伤提供科学的依据。方法采用左冠状动脉前降支结扎30min,复灌45min建立在体大鼠MIR模型。SD大鼠随机分成6组:假手术组,模型组,生理盐水组,维拉帕米组,小剂量、大剂量茶皂苷组。连续纪录Ⅱ导联心电图,于再灌注后取心尖部缺血区心肌,检测心肌细胞膜Na -K -ATP酶、Ca2 -ATP酶活性和线粒体内Ca2 含量。结果MIR损伤时,心肌细胞膜Na -K -ATP酶、Ca2 -ATP酶活性显著下降,线粒体内Ca2 含量升高;心电图ST段显著抬高,并发生明显的室性心律失常。茶皂苷可明显对抗上述变化。结论茶皂苷可通过减轻细胞内钙超载对MIR损伤起保护作用。     

二氮嗪对大鼠缺血再灌注损伤脑组织线粒体ATP酶活性的影响

目的 探讨线粒体ATP敏感性钾通道开放剂二氮嗪对大鼠局灶性脑缺血再灌注损伤脑组织线粒体ATP酶活性的影响.方法 采用改良线栓法建立大鼠局灶性大脑中动脉缺血再灌注损伤模型.将21只Wistar雄性大鼠随机分为假手术组(N组)、缺血再灌注组(IR组)、二氮嗪干预组(DZ组).缺血1 h再灌注24 h后留取标本,测定脑组织线粒体Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶活性的变化.结果 与假手术组比较,缺血再灌注组Na+-K+-ATPase、Ca2+-Mg2+-ATP酶活性明显降低(P<0.05);二氮嗪干预组Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶活性均较缺血再灌注组有不同程度的提高(P<0.05).结论 二氮嗪预处理能通过提高脑组织线粒体Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶活性,减轻脑缺血再灌注损伤,保护神经元线粒体的功能,有效维持大脑能量代谢,发挥脑保护作用.     

左旋卡尼汀对兔心肌缺血再灌注损伤的保护

目的探讨左旋卡尼汀在心肌缺血再灌注损伤状态下对心肌的保护作用。方法制备兔缺血再灌注模型,实验分为空白对照组、盐水对照组和左旋卡尼汀组,左旋卡尼汀组心肌缺血30 min后给予左旋卡尼汀。观察各组缺血再灌注过程中心电图的动态改变,以及再灌注结束后动脉血游离脂肪酸、超氧化物歧化酶、丙二醛、肌酸激酶的含量和组织中Na -K -ATP酶和Ca2 -Mg2 -ATP酶活性;用Western blot法检测结扎点以下5 mm处左心室全层心肌热休克蛋白70的含量。结果盐水对照组和左旋卡尼汀组均造成明显的心电图动态改变,与盐水对照组比较,左旋卡尼汀组心电图ST段出现有效改善;左旋卡尼汀组分别与盐水对照组和空白对照组相比,游离脂肪酸和丙二醛含量均显著减少(P<0.05);Na -K -ATP酶、Ca2 -Mg2 -ATP酶活性及超氧化物歧化酶的含量显著增多(P<0.05),肌酸激酶含量有下降趋势(P>0.05);心肌热休克蛋白70含量显著增多(P<0.05)。结论左旋卡尼汀可能诱导产生热休克蛋白70,并对心肌缺血再灌注损伤有保护作用。     

参麦注射液对心肌缺血再灌注损伤大鼠钙调神经磷酸酶活性的影响

目的探讨参麦注射液(SMI)对大鼠心肌缺血再灌注损伤(MIRI)中钙调神经磷酸酶(CaN)活性变化的影响。方法 30只大鼠随机分为假手术组、模型组和SMI组各10只,检测各组心肌CaN变化,并测定其心肌组织超氧化物歧化酶(SOD)、丙二醛(MDA)、腺苷三磷酸(ATP)、CaN活性。结果与假手术组比较,模型组CaN活性、心肌细胞凋亡率、MDA含量明显升高(P<0.01),SOD含量、Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶活性明显下降(P<0.01);与模型组比较,SMI组CaN活性、心肌细胞凋亡率、MDA含量明显下降(P<0.05),SOD含量、Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶活性明显升高(P<0.05)。结论 SMI能够抑制大鼠心肌细胞CaN活性,对缺血再灌注心肌有一定保护作用。     

地精子皂甙抗缺血再灌性心律失常的作用机制研究

目的研究地精子皂甙对心律失常的作用机制.方法借助缺血-再灌注诱发心律失常大鼠模型,观察地精子皂甙对心律失常大鼠心肌组织乳酸代谢、Ca2 浓度、脂质过氧化损伤及心肌细胞膜Na -K -ATPase和Ca2 -Mg2 -ATPase活性的影响.结果心律失常大鼠心肌组织乳酸大量堆积,脂质过氧化增强,Ca2 含量增高,而心肌细胞膜Na -K -ATPase、Ca2 -Mg2 -ATPase活性明显降低;与模型组比较,地精子皂甙大、中剂量治疗组心肌组织乳酸含量明显降低,心肌组织丙二醛(MDA)含量也明显较低,而超氧歧化酶(SOD)活性升高(P＜0.05),其中地精子皂甙大、中剂量和维拉帕米皆可明显提高心肌细胞膜Na -K -ATPase、Ca2 -Mg2 -ATPase活性,并能明显降低心肌组织Ca2 含量(P＜0.05).结论地精子皂甙具有明显抗心律失常的作用,其作用机制是通过改善缺血再灌注心肌乳酸代谢,对抗脂质过氧化损伤,提高缺血心肌细胞ATP含量,提高心肌细胞膜Na -K -ATPase、Ca2 -Mg2 -ATPase活性,抑制了Ca2 超负荷,从而发挥其抗心律失常的作用.     

诱导金属硫蛋白表达对大鼠体外心脏再灌注性心律失常的影响

目的探讨金属硫蛋白表达对大鼠体外心脏再灌注性心律失常的影响。方法将32只SD大鼠随机分成实验组、对照组,每组16只。Western blot法检测金属硫蛋白的表达;测定心肌丙二醛(MDA)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化酶(GSH-Px)水平,心肌细胞膜Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶活性及冠状动脉流出液肌酸激酶同工酶(CK-MB)的漏出率。结果与对照组比较,实验组金属硫蛋白的表达增加;心室颤动及室性心动过速持续时间缩短,心律失常的积分减少;MDA降低,SOD、CAT、GSH-Px升高;Na+-K+-ATP酶、Ca2+-Mg2+-ATP酶增加,CK-MB的漏出率减少(P<0.01)。结论金属硫蛋白表达增加可减少大鼠再灌注性心律失常,其机制可能与金属硫蛋白稳定细胞膜、抑制脂质过氧化及钙超载有关。     

步长稳心颗粒对大鼠心肌缺血再灌注心律失常的影响

目的:探索步长稳心颗粒对心肌缺血再灌注所致大鼠心律失常模型的作用。方法:结扎大鼠冠状动脉前降支得到心肌缺血再灌注心律失常模型,记录各组大鼠Ⅱ导联心电图,并测定心肌组织中Na -K -AT-Pase、Ca2 -Mg2 -ATPase的活性。结果:步长稳心颗粒对QRS时限、PR间期有稳定的作用,对抬高的ST段有降低的作用;能显著提高线粒体膜Na -K -ATPase、Ca2 -Mg2 -ATPase活性。结论:步长稳心颗粒可能是通过保持缺血-再灌注心肌细胞膜稳定性、改善缺血心肌能量代谢障碍以发挥其抗心律失常作用。     

氟中毒对小鼠心肌组织ATP酶、琥珀酸脱氢酶和总抗氧化能力的影响

目的探讨不同浓度氟化钠对小鼠心肌组织ATP酶、琥珀酸脱氢酶和总抗氧化能力的影响。方法随机挑选40只昆明小鼠,建立动态染氟模型。分别在90、120 d测定不同浓度染氟后小鼠心肌组织中Ca2+-Mg2+-ATP酶、Na+-K+-ATP酶和琥珀酸脱氢酶(SDH)活力及总抗氧化能力(T-AOC)。结果与对照组相比,过量的氟会导致小鼠心肌组织Ca2+-Mg2+-ATP酶、Na+-K+-ATP酶和SDH活力及T-AOC显著降低,各组数据差异具有统计学意义。结论氟大量蓄积引起脂质过氧化作用增强,抗氧化酶活力受到抑制,使机体处于氧化应激状态;氟中毒导致体内脂质过氧化物大量蓄积,破坏了线粒体和细胞膜通透性,导致SDH和ATP酶活性下降。     

黄龙通络胶囊对大鼠心肌缺血再灌注心律失常的影响

目的探索黄龙通络胶囊对心肌缺血再灌注所致大鼠心律失常模型的保护作用。方法采用结扎大鼠冠状动脉前降支,引起心肌缺血再灌注所致心律失常模型,记录各组大鼠Ⅱ导联心电图,并测定心肌组织中Na+-K+-ATPase、Ca2+-Mg2+-ATPase的活性。结果黄龙通络胶囊有稳定QRS间期、PR间期的作用,能降低抬高的ST段;能显著提高线粒体膜Na+-K+-ATPase、Ca2+-Mg2+-ATPase活性。结论黄龙通络胶囊可能是通过保持缺血-再灌注心肌细胞膜的稳定性,改善缺血心肌能量代谢障碍,而发挥其抗心律失常的作用。     

甲状腺功能减退大鼠心肌抗氧化能力及Na+-K+-ATP酶α1亚基mRNA表达的研究

采用低碘饮食建立甲状腺功能减退(甲减)动物模型,观察心肌抗氧化能力及Na+-K+-ATP酶α1亚基mRNA的变化,结果显示甲减大鼠心肌抗氧化能力下降,导致心肌过氧化损伤,心肌细胞萎缩,心脏内膜软骨化生,膜上参与代谢的ATP酶活性降低,Na+-K+-ATP酶α1亚基mRNA的表达下降.     

Transport of Mg2+ by Na+-Mg2+ exchange

Intracellular free Mg(2+) concentration is maintained at low levels by active extrusion from the cells. One of postulated mechanisms is the Na(+)-Mg(2+) exchange, which extrudes Mg(2+) in exchange with Na(+) influx. Although the Na(+)-Mg(2+) exchange activity has been reported in many types of cell, including neurons, details of molecular mechanisms are only poorly understood. In this chapter, we briefly will review our current knowledge on [1] stoichiometry of the Na(+)-Mg(2+) exchange, [2] interaction between the Na(+)-Ca(2+) exchange and the Na(+)-Mg(2+) exchange, [3] molecular biology of the Na(+)-Mg(2+) exchanger.     

Altered erythrocyte Na+ + K+ pump in adolescent obesity

The number of $\text{Na}\text{K}$ pump units and the cation transport activity of the pump were measured in erythrocytes from two etiologically different groups of obese adolescents and a group of normal controls. There was a significant reduction in the number of pump units, as measured by saturation ouabain binding, in erythrocytes from adolescents with idiopathic, early onset obesity. Individuals whose obesity developed subsequent to the appearance of a variety of hypothalamic lesions showed no reduction in the red cell complement of $\text{Na}\text{K}$ pump when compared to controls and the cation transport activity of their cells was higher than both the controls and the subjects with idiopathic obesity. These results support data obtained in adults that reduced red cell $\text{Na}\text{K}$ pump levels are seen in a group of individuals with idiopathic obesity. They further suggest that such reductions are not likely to be secondary to the obese state per se.     

Red blood cell Li+-Na+ countertransport, Na+-K+ cotransport, and the hemodynamics of hypertension

Red blood cell Li+-Na+ countertransport and Na+-K+ cotransport activities, home blood pressure, invasive systemic hemodynamics, and limb venous compliance were measured in 65 white men (23 normotensive, 22 borderline hypertensive, and 20 mild essential hypertensive subjects). Li+-Na+ countertransport activity was positively and significantly correlated with subject-determined home systolic blood pressure (r = 0.31, p less than 0.02) and with directly measured systolic (r = 0.29, p less than 0.02) and diastolic (r = 0.27, p less than 0.03) blood pressures in the hemodynamic laboratory, independent of potential confounding variables. Analysis of the hemodynamic determinants of blood pressure revealed a significant positive correlation of countertransport with vascular resistance (r = 0.30, p less than 0.02) but not with cardiac output or cardiac index. High red blood cell Na+-K+ cotransport activity was not independently associated with hypertension or with a characteristic hemodynamic pattern but was related to decreased venous compliance. Red blood cell Li+-Na+ countertransport deserves further study as a marker for the genetic substrate of human essential hypertension. Red cell Na+-K+ cotransport may be altered secondarily by factors related to high blood pressure and seems to be a valid marker for abnormalities of the venous system in hypertension.     

Role of intracellular Na+ in Ca2+ overload and depressed recovery of ventricular function of reperfused ischemic rat hearts. Possible involvement of H+-Na+ and Na+-Ca2+ exchange

The roles of H+-Na+ and Na+-Ca2+ exchange in the depression of ventricular function were studied in the reperfused isolated ischemic rat heart. Zero-flow global ischemia was induced for either 15 or 30 minutes and was followed by 30 minutes of aerobic reperfusion. Intracellular Na+ (Na+i) and 45Ca2+ uptake were measured during ischemia and reperfusion. Accumulation of Na+i was modified by prior glycogen depletion and by treatment with amiloride, a H+-Na+ exchange inhibitor, or monensin, a Na+ ionophore. Na+i rose continuously during ischemia and rapidly during the first two minutes of reperfusion. The larger inhibitory effect of amiloride and preischemic glycogen depletion was on Na+i accumulation during reperfusion; this finding suggests that the uptake occurs by H+-Na+ exchange. Reduction of Na+i accumulation by glycogen depletion was associated with less lactate and, presumably, H+ production and accumulation during ischemia. The rapid increase in Na+i during early reperfusion may reflect the readjustment of the low intracellular pH resulting from ischemia. The level of Na+i at the end of ischemia and especially after two minutes of reperfusion were linearly correlated with 45Ca2+ uptake and depression of ventricular function during subsequent reperfusion. This highly significant correlation between Na+i and 45Ca2+ uptake when Na+i was varied by several independent procedures, including monensin, strongly suggests that reperfusion 45Ca2+ uptake occurs at least in part by Na+-Ca2+ exchange. The rate of 45Ca2+ uptake during reperfusion was linearly and highly significantly correlated with elevation of diastolic pressure, reduced developed pressure, and decreased recovery of ventricular function. The data strongly support a mechanism of ischemic cell damage that involves excessive production and accumulation of H+ during ischemia that exchanges for extracellular Na+ during ischemia and rapidly during the first few minutes of reperfusion. Increased Na+i then causes excessive 45Ca2+ uptake and depressed recovery of cellular functions with continued reperfusion. Increased levels of Na+i may be a major event that couples a decreased intracellular pH during ischemia to excessive 45Ca2+ uptake and depressed recovery of cellular function with reperfusion.     

Developmental changes of sarcolemmal Na+-H+ exchange

We previously demonstrated that the effect of respiratory acidosis on cardiac contractility in the newborn was less than in the adult rabbit, and these data suggested a higher [Na+]i and [Na+]i-[Ca2+]o exchange in the newborn as compared to the adult. In this study, we investigated developmental changes of Na+-H+ exchange in isolated sarcolemmal vesicles. Sarcolemmal purification for Na+-K ATPase was 61.9 and 67.1 fold in the newborn and the adult rabbit heart, respectively. In the presence of an outwardly directed proton gradient across the vesicular membrane, sarcolemmal 22Na uptake rate in the newborn (0.22 +/- 0.01 nmol Na+/mg prot/s) was significantly higher than than in the adult (0.16 +/- 0.01 nmol Na+/mg prot/s). 1.0 mM amiloride inhibited 22Na uptake by 75% and 80% in the newborn and the adult, respectively. In the absence of a pH gradient, vesicular 22Na uptake in the newborn and the adult were not significantly different. In conclusion, the higher Na+-H+ exchange in the newborn may lead to a higher [Na+]i and subsequent calcium influx via Na+-Ca2+ exchange as compared with the adult during acidosis. This may explain the greater recovery of mechanical function in the newborn heart as compared to the adult heart during acidosis.     

钠氢交换泵抑制剂的神经保护作用

Na+-H+交换泵(NHE)是一种在脑内普遍存在的蛋白,生理和病理条件下参与调节pH.研究显示,Na+-H+交换泵抑制剂对缺血再灌注动物模型的脯损伤有显著的保护作用.Na+-H+交换泵抑制剂可能通过抑制Na+-H+交换,防止细胞内Ca2+超负荷和其他相关作用,对缺血性脑损伤起保护作用.     

Difference between human red blood cell Na+-Li+ countertransport and renal Na+-H+ exchange

Several laboratories have reported that the activities of sodium-lithium countertransport are increased in red blood cells from patients with essential hypertension. Based on the many similarities between this transport system and the renal sodium-proton exchanger, a hypothesis has been put forth in the literature that increased red blood cell sodium-lithium countertransport activity may be a marker for increased sodium-proton exchange activity in the renal proximal tubule. The present studies were designed to test the hypothesis that sodium-lithium countertransport in red blood cells from humans or rabbits is mediated by the same transport mechanism that mediates sodium-proton exchange in the renal brush border from those species. Similar to what has been reported for the rabbit, the present studies show that an amiloride-sensitive sodium-proton exchanger is present in human renal brush border vesicles. However, Na+-Li+ countertransport in human and rabbit red blood cells, assayed under several different conditions, was not inhibited by amiloride. In agreement with what has been reported for humans, the present studies show that extracellular proton-stimulated sodium efflux is inhibited by amiloride in rabbit red blood cells. These data demonstrate a difference (amiloride sensitivity) between the red blood cell sodium-lithium countertransporter and the renal brush border sodium-proton exchanger in humans and rabbits. These experiments detract from the hypothesis that increased red blood cell sodium-lithium countertransport activity in patients with essential hypertension is a marker for increased sodium-proton exchange activity in the renal brush border.     

Inhibition by Lanthanum of the Na+ + K+ activated, ouabain-sensitive adenosinetriphosphatase enzyme.

The effect of La³⁺ on the activity of a Na⁺ + K⁺—activated, ouabain-sensitive ATPase enzyme isolated as a microsomal fraction from guinea pig heart muscle has been investigated. Ten to 100 μmLa³⁺ has a dose-dependent, uncompetitive inhibitory effect, approximately 100 fold greater than that caused by equimolar concentrations of Ca²⁺. The activity of the ouabain-insensitive ATPase enzyme is not affected. The same concentrations of La³⁺ failed to alter the ³⁺H-ouabain binding capacity of the microsomal fraction. These results are interpreted to mean that La³⁺ and ouabain interact with different receptor sites and that La³⁺ has other actions apart from its well recognized Ca²⁺—antagonist activity.     

肝硬化红细胞钠钾ATP酶、钙镁ATP酶及钠钾钙镁改变

目的:探讨肝硬化时细胞内钠钾钙镁的改变及细胞膜钠钾ATP酶(NKA)、钙镁ATP酶 (CMA)活性改变在细胞内钠钾钙镁改变中的作用．方法:测定了52例肝硬化失代偿期(实验组 A)、36例代偿期(实验组B)患者红细胞及血清钠钾钙镁(RNa、RK、RCa、RMg;SNa、 SK、SCa、SMg)含量和NKA和CMA活性．以 36名健康人为对照组．结果:与对照组比较,实验组A的NKA、 CMA、RK、RMg(t=5．92,P<0．001;t=7．21, P<0．001;t=2．32,P<0．02;t=4．79,P<0．001)和买验组B的NKA、CMA、RK、RMg(t=3．83, P<0．001;t=2．53,P<0．02;t=2．03,P<0．05;t= 3．33,P<0．002)均显著降低;与实验组B比较, 实验组A的NKA、CMA活性(t=2．29,P<0．05; t=4．14,P<0．005)显著降低．与对照组比较, 买验组A的SNa、SK、SCa、SMg(t=8．25, P<0．001;t=5．73,P<0．001;t=9．82,P<0．001; t=6．15,P<0．001)显著降低;与实验组B比较, 买验组A的SNa、SK、SCa、SMg(t=6．94, P<0．001;t=5．00,P<0．001;t=5．57,P<0．001; t=5．73,P<0．001)显著降低．与Child B级组比较,Child C级组的NKA、CMA、RK、RMg、 SNa、SK、SCa、SMg(P<0．05或P<0．01) 显著降低．与非肝性脑病组比较,肝性脑病组NKA、CMA、RK、RMg、SNa、SK、 SMg(P<0．05或P<0．01)显著降低．实验组A中, 低SMg者的NKA和CMA显著低于高SMg者 (16．87±3．19 vs 19．04±3．25;109．83±13．51 vs 120．13±13．27;P均<0．05)．结论:肝硬化患者存在缺钾缺镁,且随病情加重而加重,缺钾缺镁可能为病情加重的原因之一．NKA和CMA活性降低可导致细胞内低钾低镁和钠钙蓄积．缺镁为ATP酶活性在失代偿期进一步降低的原因之一．