爱大霉素和庆大霉素对肾皮质线粒体~(45)Ca~(2+)摄取的影响

目的研究爱大霉素和庆大霉素对大鼠肾皮质线粒体钙摄取的影响。方法应用４５Ｃａ２＋示踪技术。结果两药在１ｍｍｏｌ·Ｌ－１时显著促进线粒体钙摄取（分别由每３０ｍｉｎ（１１３．５±７．５）μｍｏｌ·ｇ－１Ｐｒｏ上升到（１４８．０±２４．０）μｍｏｌ·ｇ－１Ｐｒｏ，（１１１．９±１３．０）μｍｏｌ·ｇ－１Ｐｒｏ上升到（１４０．１±１６．６）μｍｏｌ·ｇ－１Ｐｒｏ，Ｐ＜０．０５）；在１０μｍｏｌ·Ｌ－１时显著抑制线粒体钙摄取（分别由每３０ｍｉｎ（１１３．５±７．５）μｍｏｌ·ｇ－１Ｐｒｏ下降到（９２．３±５．７）μｍｏｌ·ｇ－１Ｐｒｏ，（１１１．９±１３．０）μｍｏｌ·ｇ－１Ｐｒｏ下降到（１４０．０±５．３）μｍｏｌ·ｇ－１Ｐｒｏ，Ｐ＜０．０５或Ｐ＜０．０１）。结论两药对线粒体钙摄取的这种双相变化可能与它们肾毒性有关     

The uptake and O-methylation of 3H-(±)-isoprenaline in rat cerebral cortex slices

Summary The O-methylation and accumulation of ³H-isoprenaline in slices of the rat cerebral cortex were studied before and after inhibition of COMT. 1. Inhibition of COMT by mol/l U-0521 virtually abolished the O-methylation and increased the accumulation of ³H-isoprenaline; hence, there is evidence for the existence of a central O-methylating system (with a transport mechanism and intracellular COMT). 2. Experiments were carried out with selective uptake inhibitors for uptake, (cocaine and desipramine) or uptake2 (corticosterone and OMI), with phenoxybenzamine (known to inhibit both carriers) and with changes in the ionic composition of the incubation medium. They revealed that the central carrier differed from both, uptake, and uptake2, although exhibiting some resemblance with uptake₂ (lack of dependence on Na⁺ and Cl^–, sensitivity to K⁺ and phenoxybenzamine, ability to transport ³H-isoprenaline). 3. Although the central carrier was rather sensitive to inhibition by beta-adrenoceptor antagonists (propranolol, carteolol), the effect of propranolol was not stereoselective; hence, beta-adrenoceptors do not seem to be involved. 4. Virtually identical IC₃₀-values were obtained for inhibitors, when determined with or without inhibition of COMT. Only OMI was found to inhibit COMT as well as the central transport system; hence it was more potent in inhibiting the O-methylation than the accumulation of ³H-isoprenaline. 5. IC₅₀-values (against initial rates of accumulation of ³H-isoprenaline; COMT inhibited) were determined for various substrates and inhibitors of peripheral uptake₂. There was no correlation with the IC₅₀-values determined earlier for uptake2 in rat heart (Grohmann and Trendelenburg 1984). 6. Unlabelled catecholamines half saturated the intracellular COMT when slices were incubated with 0.22 mol/l [(±)-dobutamine] to 4.9 mol/l [(–)-noradrenaline]. As the presence of unlabelled catecholamines increased tissue levels of ³H-isoprenaline, catecholamines are substrates of the central carrier. 7. The carrier of the central O-methylating system differs from uptake₂ of peripheral organs, although it resembles the peripheral carrier in some respects.Abbreviations COMT catechol-O-methyl transferase - DOPEG dihydroxyphenylglycol - MAO monoamine oxidase - OMI 3-Omethyl-isoprenaline Supported by the Deutsche Forschungsgemeinschaft (Tr 96 and SFB 176) and by a scholarship of the Royal Society for V. G. Wilson. Some of the results were presented to the British Pharmacological Society (Trendelenburg and Wilson 1986)     

Axin1调节骨骼肌GLUT4蛋白表达的作用研究

目的：探讨体轴发育抑制因子（Axin1）调节骨骼肌葡萄糖转运蛋白4(GLUT4)蛋白表达的作用及其机制。方法：利用RNAi干扰的Axin1腺病毒（Ad-siAxin1）感染C2C12小鼠骨骼肌细胞敲低Axin1,荧光显微镜和MTS实验明确Ad-siAxin1最佳感染浓度和时间。分别用携带绿色荧光蛋白的腺病毒（Ad-GFP）、Ad-siAxin1、载体质粒（vector）和Axin1质粒转染C2C12小鼠骨骼肌细胞敲低或过表达Axin1蛋白,Western印迹检测Axin1、端锚聚合酶蛋白（TNKS）和GLUT4蛋白水平。结果：荧光显微镜和MTS实验结果显示,在C2C12小鼠骨骼肌细胞中Ad-siAxin1作用的最佳浓度和时间分别为160μL和48 h。Western印迹结果显示,与Ad-GFP组相比,Ad-siAxin1组中Axin1蛋白降低（t=6.746,P<0.01）。Ad-siAxin1组TNKS蛋白水平降低（t=4.019,P<0.05）,GLUT4蛋白水平下调（t=3.248,P<0.05）。与vector组相比,转染Axin1质粒后,Axin1蛋白水平上...     

Uptake inhibitors do not change the effect of imidazoline α2-adrenoceptor agonists on transmitter release evoked by single pulse stimulation in mouse vas deferens

Summary The present study was undertaken to compare the presynaptic interaction of neuronal noradrenaline uptake inhibitors with imidazoline and phenylethylamine ₂adrenoceptor agonists under two different conditions: at low and high noradrenaline concentrations in the biophase.Isolated mouse vasa deferentia were stimulated with trains of 7 pulses given at 0.2 Hz and the inhibition by the ₂-adrenoceptor agonists clonidine, -methylnoradrenaline, and UK-14,304 of twitch responses was measured in the absence and in the presence of either cocaine (12 mol/l) or desipramine (40 nmol/l). The effects were determined for the first (equivalent to single pulse stimulation) and the last stimulus of each train. Both uptake inhibitors antagonized the presynaptic inhibitory effects of imidazolines (clonidine and UK-14,304) on the last twitch; the effects on the first twitch remained unchanged. In contrast, the uptake inhibitors potentiated the inhibitory effect of the phenylethylamine (-methylnoradrenaline) on both the first and the last twitches.These results support the view that the concentration of noradrenaline in the biophase plays a decisive role in the inhibition by a₂-adrenoceptor agonists of the electrically evoked release of noradrenaline. Agonists that are not substrates of neuronal uptake (i.e., clonidine, UK-14,304) become less effective when noradrenaline is present in the biophase while substrates of neuronal uptake (i. e., -methylnoradrenaline) do not. The results argue against the hypothesis that uptake inhibitors interact directly with presynaptic ₂-adrenoceptors or act at some link between uptake and receptor sites. Send offprint requests to S. Guimarães at the above address     

Ontogenetic profile of glutamate uptake in brain structures slices from rats: sensitivity to guanosine

The excitotoxicity of the neurotransmitter glutamate has been shown to be connected with many acute and chronic diseases of the CNS. High affinity sodium-dependent glutamate transporters play a key role in maintaining adequate levels of extracellular glutamate. In the present study, we used slices of striatum, hippocampus and cortex from rat brain to describe the in vitro profile of glutamate uptake during development and ageing, and its sensitivity to guanosine. In all structures, glutamate uptake was higher in immature animals. There was a maximum decrease in glutamate uptake in striatum and hippocampus in 15-month-old rats, which later increased, while in cortex there was a significant decrease in rats aged 60 days old. The effect of guanosine seems to be age and structure dependent since the increase in basal glutamate uptake was only seen in slices of cortex from 10-day-old animals.     

Subsynaptosomal distribution of calcium during aging and 3,4-diaminopyridine treatment

Since previous studies showed that calcium uptake by synaptosomes from rodents declines with aging [30], the subsynaptosomal distribution of calcium was determined with the disruption method of Scott et al. [37]. Calcium uptake by the mitochondrial (digitonin-resistant) and non-mitochondrial (digitonin-labile) compartments, as well as total uptake, were determined at 2, 5 and 10 min. After a 10 min incubation under resting conditions (5 mM-KCl), total calcium uptake decreased at 10 months (−14.6%) and 30 months (−33.0%) of age; mitochondrial calcium uptake increased by 10 months (+11.2%) but declined by 30 months (−17.5%); the nonmitochondrial calcium compartment declined at 10 (−34.7%) and 30 (−43.4%) months when compared to the 3 month old control. With potassium depolarization (31 mM-KCl), total calcium uptake declined from 100% (3 months) to 73.8% (10 months) or 53.0% (30 months); mitochondrial calcium uptake declined from 100% (3 months) to 85.6% (10 months) or 68.4% (30 months); non-mitochondrial calcium uptake decreased at 10 (−34.3%) and 30 (−57.7%) months of age when compared to 3 months (100%). The deficits in calcium homeostasis are not due to changes in synaptosomal volumes or to diminished membrane potentials, as assessed by tetraphenylphosphonium ion accumulation. 3,4-Diaminopyridine partially reversed the alterations in total, mitochondrial and non-mitochondrial calcium uptake by synaptosomes from aged mice.     

Renal hemodynamics and renal O2 uptake during hypoxia in the anesthetized rabbit

Summary The effects of hypoxic hypoxia on renal hemodynamics and metabolism have been studied in anaesthetized mechanically ventilated rabbits. Acute hypoxia (F₁O₂=0.10,PaO₂=35 torr) induces at constant mean arterial pressure a 45% decrease in RBF, GFR, and whereas free water clearance increases. These alterations were still apparent 50 min after resuming normal arterial oxygenation. In order to assess the role of the stimulation of catecholamine release in these observations, two other sets of experiments were performed: 1) the animals were ventilated with the same hypoxic gas mixture but after adrenergic blockade (phentolamine: 0.2 mg·kg·min^–1 i.v.), 2) hypoxia was induced by ventilating the animals with CO (F_ICO=0.002) at constantPaO₂. Increase in renal vascular resistance and reduction of renal O₂ uptake were still observed. This indicates that adrenergic stimulation cannot fully explain the renal vasoconstriction encountered in hypoxia. The role of a local vasoactive factor, especially that of the renin angiotensin system is discussed. The apparent O₂ cost of Na reabsorption was not greatly modified by any type of hypoxia and the Na:O₂ ratio remained close to the value observed in normoxic animals. This indicates that the kidney may adapt to hypoxia by reducing its O₂ demand keeping unaltered its tubular function and basal O₂ needs.     

Characterization of acetate uptake by the colonic epithelial cells of the rat

The characteristics of acetate uptake by colonic epithelial cells of the rat were studied. Clear saturation kinetics of acetate uptake were not observed in these experiments at either 0° C or 30° C. A decrease in the pH of the medium markedly increased the acetate uptake. The activation energy for acetete uptake derived from an Arrhenius plot was about 6.1 kcal/mole. Among the inhibitors tested, no effective inhibition of acetate uptake at 0° C was observer. Metabolic inhibitors severely inhibited transport at 30° C. Inhibition of acetate uptake by other short chain fatty acids, which was non-competitive, was observed. The finding that efflux from the cells was stimulated in the presence of compounds such as pyruvate and bicarbonate supported the notion of a close interrelationship between weak electrolyte transports in vivo. Although the H⁺ gradient across the cell membrane is suggested to be one of the factors determining the uptake rate, it seems difficult to explain all the results in this way.     

Changes in blood lactate and respiratory gas exchange measures in sports with discontinuous load profiles

This study compares two different sport events (orienteering = OTC; tennis = TEC) with discontinuous load profiles and different activity/recovery patterns by means of blood lactate (LA), heart rate (HR), and respiratory gas exchange measures (RGME) determined via a portable respiratory system. During the TEC, 20 tennis-ranked male subjects [age: 26.0 (3.7) years; height: 181.0 (5.7) cm; weight: 73.2 (6.8) kg; maximal oxygen consumption (V˙O₂max): 57.3 (5.1) ml·kg⁻¹·min⁻¹] played ten matches of 50 min. During the OTC, 11 male members of the Austrian National Team [age: 23.5 (3.9) years; height: 183.6 (6.8) cm; weight: 72.4 (3.9) kg; V˙O₂max: 67.9 (3.8) ml·kg⁻¹·min⁻¹] performed a simulated OTC (six sections; average length: 10.090 m). In both studies data from the maximal treadmill tests (TT) were used as reference values for the comparison of energy expenditure of OTC and TEC. During TEC, the average V˙O₂ was considerably lower [29.1 (5.6) ml^·kg^−1·min⁻¹] or 51.1 (10.9)% of VO₂max and 64.8.0 (13.3)% of V˙O₂ determined at the individual anaerobic threshold (IAT) on the TT. The short high-intensity periods (activity/recovery = 1/6) did not result in higher LA levels [average LA of games: 2.07 (0.9) mmol·l⁻¹]. The highest average V˙O₂ value for a whole game was 47.8 ml·kg^−1·min⁻¹ and may provide a reference for energy demands required to sustain high-intensity periods of tennis predominately via aerobic mechanism of energy delivery. During OTC, we found an average V˙O₂ of 56.4 (4.5) ml·kg⁻¹·min⁻¹ or 83.0 (3.8)% of V˙O₂max and 94.6 (5.2)% of V˙O₂ at IAT. In contrast to TEC, LA were relatively high [5.16 (1.5) mmol·l⁻¹) although the average V˙O₂ was significantly lower than V˙O₂ at IAT. Our data suggest that portable RGEM provides valuable information concerning the energy expenditure in sports that cannot be interpreted from LA or HR measures alone. Portable RGEM systems provide valuable assessment of under- or over-estimation of requirements of sports and assist in the optimization and interpretation of training in athletes. Electronic Publication     

急性冠周炎患者冷疗前后的免疫状态研究

本文采用液氮浅低温冷冻疗法治疗５０例急性冠周炎患者，取得了良好临床效果，并于冷疗前后对血及唾液中ＩｇＧ、ＩｇＡ、ＩｇＭ和血中Ｃ３及淋巴细胞转化率进行了免疫状态研究。实验结果表明，冷疗后系列免疫指标明显增高。故认为冷冻治疗冠周炎的主要机理是提高机体的免疫功能。