Activation of L-arginine transport in undialysed chronic renal failure and continuous ambulatory peritoneal dialysis patients

1. Treatment with haemodialysis and continuous ambulatory peritoneal dialysis (CAPD) presents different pathophysiological profiles and it has been suggested that clinical outcome in chronic renal failure may depend on the mode of dialysis. The transport of L-arginine, a precursor of nitric oxide, into blood cells is increased in uraemic patients on haemodialysis. The present study was designed to investigate L-arginine transport into red blood cells (RBC) in uraemic patients not yet on dialysis and on CAPD therapy. 2. Eleven uraemic patients not yet on dialysis and 17 on CAPD were included in the study. L-Arginine transport into RBC and plasma and RBC amino acid profiles were analysed in these sets of patients. 3. L-Arginine transport via system y(+), but not y(+)L, into RBC, was significantly increased in undialysed uraemic patients (459 +/- 40 micromol/L per cell per h) and CAPD patients (539 +/- 61 micromol/L per cell per h) compared with controls (251 +/- 39 micromol/L per cell per h). High-pressure liquid chromatography measurements demonstrated low levels of plasma L-arginine in uraemic patients both on CAPD (54 +/- 3 micromol/L) and not yet on dialysis (80 +/- 6 micromol/L) compared with control subjects (146 +/- 14 micromol/L). 4. Our findings provide the first evidence that uraemic patients not yet on dialysis and on CAPD present with an activation of L-arginine transport via system y(+) into RBC associated with reduced plasma levels of L-arginine.     

Studies on the effect of ethanol and/or toluene on rat erythrocytes

Rats were subjected to a chronic ethanol exposure in their drinking water for 8 months and then a short subacute toluene exposure to 12,000 mg/m3 for 5 h/day for nine days. Combined exposure increased the reticulocyte count and the concentration of haemoglobin, and changed the biochemical/biophysical properties of red blood cells. Macrocytosis and a decrease in erythrocyte membrane lipid fluidity in the middle zone of the lipid bilayer were the most useful indices of exposure.     

Pravastatin has no direct effect on transmembrane cationic transport systems in human erythrocytes and platelets

In vitro incubation of human erythrocytes and platelets with the 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor pravastatin in the concentration range 1 nM to 10μM did not affect the activity of the Na⁺−K⁺-pump, Na⁺−K⁺-cotransport or Na⁺−Li⁺-countertransport, or the ground membrane leak for Na⁺ and K⁺. The data indicate that pravastatin has no direct effect on transmembrane cationic transport systems in red blood cells or platelets.     

Interaction of acrylamide with glutathione in rat erythrocytes

Evidence is presented for an enzyme-catalyzed conjugation of acrylamide (ACR) in rat erythrocytes. Daily exposure of rats to ACR for a period of 7, 14 and 21 days resulted in a time-dependent decrease in glutathione content. In vitro incubation of ACR with rat erythrocytes suspension caused a concentration-dependent decrease in glutathione levels. Red blood cell (RBC) enzyme-catalyzed conjugation of ACR with glutathione increased with protein concentration and was dependent on pH and time of incubation. Glutathione-S-transferase (GST) activity using acrylamide and 1-chloro 2,4-dinitrobenzene (CDNB) as substrates followed the order: liver > kidney > brain > erythrocytes. Glutathione peroxidase activity of RBCs was inhibited by the in vitro addition of ACR to erythrocytes. These results suggest that rat erythrocytes are equipped with the mechanism which can inactivate toxic electrophilic chemicals, such as acrylamide.     

Transport of nitric oxide synthase inhibitors through cationic amino acid carriers in human erythrocytes

The interaction of arginine analogues, which are known to inhibit nitric oxide synthase, with two cationic amino acid transporters of human erythrocytes (systems y⁺ and y⁺L) was studied. Arginine and relevant analogues [N^G-monomethyl-L-arginine (L-NMMA); N^G-monomethyl-D-arginine (D-NMMA) and N^G-nitro-L-arginine (L-NOARG)] were found to inhibit labeled lysine influx into intact erythrocytes. As expected, the pattern of inhibition reflected the contribution of the two distinct transport systems. All analogues showed a higher affinity for system y⁺L than for system y⁺. The half-saturation (inhibition) constants estimated for systems y⁺ and y⁺L (±SEM) were (μM): -arginine, 55.7 ± 5.4 and 2.4 ± 0.1; -NMMA, 151 ± 13 and 7.5 ± 0.5; -NMMA, 2660 ± 404 and 269 ± 25; -NOARG, 9414 ± 169 and 594 ± 35. The transport properties of the analogues were investigated using an assay based on the trans-stimulation of lysine efflux. The addition of saturating concentrations of unlabeled analogues to the external medium stimulated efflux of labeled lysine through systems y⁺L and y⁺, showing that the analogues can enter the cell through these pathways.     

In vitro effect of cilazaprilat on sodium-potassium transport systems in human erythrocytes

The in vitro effects of cilazaprilat in a concentration range of 10 nM to 1 mM were investigated on various Na+ and K+ transport systems in human red blood cells. Cilazaprilat inhibited the anion carrier or DIDS-sensitive LiCO3(-)-influx and the bumetanide-sensitive K(+)-efflux. However, no effect of cilazaprilat on the Na+, K(+)-pump activity, the number of active Na+ pump units and on the Na+, Li(+)-countertransport activity could be demonstrated. It is suggested that through a decreased anion carrier indicating a decreased Na(+)-influx, the lower intracellular Na+ concentration observed in vivo during angiotensin-converting enzyme inhibition, can be at least partly explained.     

In vitro effect of xipamide on sodium-potassium transport systems in human erythrocytes

The in vitro effects of xipamide in a concentration range of 10(-8) to 10(-2) M were investigated on various Na+ and K+ transport systems in human red blood cells. Xipamide inhibited the anion carrier or DIDS-sensitive LiCO3- -influx starting from a concentration of 10(-5) M. However, a decrease in the Na+, K+-pump and the Na+, K+-cotransport activity and a rise in the passive permeability of the cell membrane was only observed starting from a concentration of 10(-4) M xipamide.     

Role of nitric oxide in adrenocorticotrophin-induced hypertension: L-arginine effects reversed by N-nitro-L-arginine

1. L-arginine prevents adrenocorticotrophin (ACTH)-induced hypertension in the rat. To confirm that this effect is mediated through the nitric oxide (NO) system, we examined whether N-nitro-L-arginine (NOLA) could reverse the L-arginine-induced blockade of ACTH-induced hypertension. 2. Blood pressure and metabolic parameters were examined in sham-, ACTH-, L-arginine + sham-, NOLA + sham-, ACTH + L-arginine- and ACTH + L-arginine + NOLA-treated Sprague-Dawley rats (n = 40). 3. Adrenocorticotrophin treatment increased systolic blood pressure (SBP), water intake and urine output and decreased bodyweight. N-Nitro-L-arginine alone increased SBP without affecting metabolic variables. L-Arginine alone did not affect blood pressure. The SBP was lower in L-arginine + ACTH- than ACTH-treated rats (P < 0.001), but was higher following ACTH + L-arginine + NOLA than ACTH + L-arginine (P < 0.05). 4. N-Nitro-L-arginine reversed the blood pressure-lowering effect of L-arginine in ACTH-induced hypertension in the rat, supporting the notion that NO plays a role in the hypertension.     

Effects of diethyltindichloride on amino acid and nucleoside transport in suspended rat thymocytes

The effects of diethyltindichloride (DETD) on basic biochemical processes of thymus cells were investigated in order to develop an understanding of the mechanism by which dialkyltins act on the thymus of rodents in vivo. Accumulation of the nonmetabolizable amino acid α-aminoisobutyrate (AIB) was markedly inhibited by the dialkyltins in suspended rat thymocytes. The inhibitory effects on AIB influx were apparent after as little as 5 min of thymocyte preincubation with DETD. Low dialkyltin concentrations, which did not inhibit AIB influx in noninsulin-stimulated cells, abolished the insulin-mediated AIB influx. Addition of lipoic acid (reduced) to the incubation medium prevented the inhibitory action of DETD on AIB influx. DETD markedly inhibited labeled thymidine incorporation into DNA of suspended rat thymocytes, possibly via inhibition of transmembrane transport of this nucleoside precursor. In sharp contrast to its effect on thymidine incorporation, DETD stimulated the incorporation of labeled uridine into RNA.     

L-精氨酸对局灶性脑缺血大鼠脑组织氨基酸含量的影响

目的观察L-精氨酸对脑缺血大鼠纹状体、海马、皮层中天门冬氨酸(Asp)、谷氨酸(Glu)、甘氨酸(Gly)、γ-氨基丁酸(GABA)含量的影响,探讨L-精氨酸对大鼠脑缺血组织的保护作用及其作用机制。方法采用线栓法复制大鼠中脑动脉梗塞(MCAO)模型,缺血后给予L-精氨酸治疗。相应时间断头取脑,然后测定脑梗死体积、脑组织中氨基酸的含量。结果L-精氨酸组脑梗死体积较缺血组明显缩小;与假手术组比较,缺血组纹状体、海马、皮层中Asp、Glu、Gly、GABA含量显著增加,给予L-精氨酸治疗后,缺血后2、6h治疗组Asp、Glu的含量明显降低,Gly、GABA含量明显升高。结论L-精氨酸降低脑组织中兴奋性氨基酸的含量及升高抑制性氨基酸的含量可能是保护脑缺血的重要机制。     

The lack of active bile acid transport in AS-30 D ascites hepatoma cells

Summary The uptake of cholic acid as well as taurocholic acid into AS-30 D ascites hepatoma cells showed linearity with respect to incubation concentrations. It has been suggested that these processes can be described as simple diffusion. In further experiments it could be shown that ascites hepatoma cells were unable to conjugate cholic acid. These results may have significance in the phalloidin action on hepatocytes.     

安阳地区血液制剂容量控制中标示量范围的确定

目的探讨安阳地区血液制剂容量控制中标示量的范围,为临床输血工作提供可靠的数据支持。方法根据《全血及成分血质量要求GB18469—2001》中容量标准要求结合安阳地区血液制剂制备实际情况,确定出符合安阳地区血液制剂容量标准的标示量范围,并将确定出的标示量范围与实际制备的血液制剂容量进行比对。结果安阳地区来源于400ml全血的去白全血容量标示范围确定为（460±46）ml;来源于400ml全血的2U去白悬浮红细胞容量标示范围确定为（300±30）ml;来源于200ml全血的1U去白悬浮红细胞容量标示范围确定为（150±15）ml。安阳地区实际制备的血液制剂容量85％以上都在确定的标示量范围内。结论安阳地区血液制剂容量符合国家标准要求,建议在血液制剂标签上注明标示量范围,血液制剂标示量范围的准确标定具有重要的临床意义。     

The effect of pentoxifylline on filterability of normal red blood cells and their adhesiveness to cultured endothelial cells

Summary The effects of pentoxifylline on filterability of normal red blood cells (RBCs) and their adhesiveness to cultured endothelial cells were investigated.1. In a balanced randomized and double blind trial, six healthy volunteers received 400 mg pentoxifylline or matching placebo 2 h before blood samples were taken. Filterability of RBCs of the subject while on pentoxifylline was significantly increased at 25 °C and 18 °C.2. Lowering of the filteration temperature to 18 °C significantly decreased filterability of RBCs.3. In vitro studies showed that 12 µg/ml pentoxifylline significantly increased RBC filterability and also partially prevented the effect of decreasing temperature on RBC filterability.4. 12 µg/ml pentoxifylline significantly decreased the adherence of normal RBCs to cultured endothelial cells.Our results suggest that in addition to increasing filterability of RBCs, pentoxifylline also decreased the adherence of RBCs to endothelial cells and this may contribute to its therapeutic effect.     

In vitro sub-hemolytic effects of butoxyacetic acid on human and rat erythrocytes.

When 2-butoxyethanol (2-BE) is administered to rats, hemolysis occurs as the active metabolite butoxyacetic acid (BAA) is formed. Human red blood cells appear to be relatively resistant to the hemolytic effects of BAA in vitro, whereas rat red blood cells undergo changes in deformability, cell swelling, and hemolysis. In this study, exposure of human red blood cells to high concentrations of BAA resulted in loss of deformability and a small increase in mean cellular volume, but no significant hemolysis. These changes resembled the changes that occur in rat erythrocytes exposed to much lower concentrations of BAA. Therefore, a comparison was made between the sub-hemolytic effects of BAA at high concentrations (up to 10 mM) on human red cells with the sub-hemolytic effects of lower concentrations of BAA (up to 0.1 mM) on rat erythrocytes. Under these conditions, human and rat erythrocyte deformability decreased, while mean cellular volume (MCV) and osmotic fragility increased. Although there was a substantial shift in rat erythrocytes to lower densities, human erythrocyte density was only slightly decreased. Human and rat erythrocyte sodium also increased. Rat erythrocytes demonstrated increased spherocytosis. In a survey of blood samples from adults and children, none demonstrated an increase in hemolysis (n = 97) or MCV (n = 65) after exposure to 10 mM BAA for 4 h. In these experiments, in which hemolysis was not evident, human erythrocytes required exposure to a 100-fold greater concentration of BAA to develop changes in red cell deformability, osmotic fragility, and sodium content similar to those observed in rat erythrocytes. These concentrations are not likely to occur under normal human use of 2-BE-containing products.     

Stem bark and flower extracts of Vismia cauliflora are highly effective antioxidants to human blood cells by preventing oxidative burst in neutrophils and oxidative damage in erythrocytes

Abstract

Context: Vismia cauliflora A.C.Sm. [Hypericaceae (Clusiaceae)] is an Amazonian plant traditionally used by indigenous population to treat dermatosis and inflammatory processes of the skin. Previous research on V. cauliflora extracts suggests its potential to neutralize cellular oxidative damages related to the production of reactive oxygen and nitrogen species.

Objective: To determine the activity of stem bark and flower extracts of V. cauliflora on the modulation of oxidative burst in human neutrophils, as well as its potential to inhibit oxidative damage in human erythrocytes.

Materials and methods: The modulation of neutrophil’s oxidative burst by the ethanolic extracts (0.3–1000?µg/mL) was determined by the oxidation of specific probes by reactive species. Additionally, the potential of these extracts to inhibit oxidative damage in human erythrocytes was evaluated by monitoring its biomarkers of oxidative stress.

Results: Vismia cauliflora extracts presented remarkable capacity to prevent the oxidative burst in activated human neutrophils (IC₅₀?<?15?µg/mL). However, the maximum percentage of inhibition achieved against hydrogen peroxide was 45%. Concerning the oxidative damage in human erythrocytes, the extracts were able to minimize the tert-butyl hydroperoxide-induced hemoglobin oxidation and lipid peroxidation in a very low concentration range (2.7–18?μg/mL). Furthermore, only stem bark extract (100?µg/mL) was able to inhibit the depletion of glutathione (13%).

Discussion and conclusion: These results reinforce the therapeutic potential of stem bark and flower extracts of V. cauliflora to heal topical skin disease, namely in the treatment of neutrophil-related dermatosis and skin conditions related to oxidative stress, including skin aging.     

Antinociceptive effect of L-arginine on the carrageenin-induced hyperalgesia of the rat: possible involvement of central opioidergic systems.

L-arginine is considered to be a precursor substance of kyotorphin (tyrosyl-arginine), a [Met5]enkephalin releaser with antinociceptive action. We examined the antinociceptive effect of L-arginine in rats. L-Arginine (300-1000 mg/kg) administered subcutaneously (s.c.) elicited antinociception (assessed by the Randall-Selitto method) in rats with a carrageenin-treated hindpaw. Naloxone (2 mg/kg s.c.) but not N-methyl-levallorphan (20 mg/kg s.c.), a peripherally selective opioid antagonist, inhibited L-arginine-induced antinociception. Intracerebroventricular administration of L-arginine (0.2-1.0 mg/rat) produced a dose-related inhibition of the carrageenin-induced hyperalgesia. Intraplantar (i.pl.) injection of L-arginine (0.5-1.0 mg/paw) also induced antinociception, which was resistant to naloxone (2 mg/kg s.c.) but was antagonized by methylene blue (0.5 mg/paw i.pl.), a guanylate cyclase inhibitor. L-Arginine (1000 mg/kg s.c.) did not inhibit edema formation in the carrageenin-treated rat hindpaw. These results suggest that systemically administered L-arginine produces mainly an antinociceptive effect mediated by central opioidergic mechanisms in rats with carrageenin-induced hyperalgesia.     

柠檬总提取物对正常大鼠及SHR血压、血脂影响的实验研究

目的:研究安岳柠檬总提取物对正常及自发性高血压大鼠(SHR)血压、血脂水平的影响.方法:柠檬总提取物6.0 g·kg-1、3.6g·kg-1、2.16 g·kg-1连续灌胃给药21 d,颈动脉插管法观察对正常大鼠血压的影响,测定血清葡萄糖(GLU)、甘油三酯(TG)、血清总胆固醇(TC)含量;连续灌胃给药28 d,分别于给药7、14、21、28 d无创法测定SHR的血压,测定给药28 d后血清GLU、TG、TC含量.结果:柠檬总提取物6.0 g·kg-1对正常麻醉大鼠具有降血压作用,但对SHR血压无显著影响;各剂量组对正常大鼠、SHR血清TG含量有显著降低作用.结论:柠檬总提取物具有明确的降低TG含量作用,改善血脂代谢;其降血压作用的发挥可能与给药途径有关,有待进一步验证.     

缺血—再灌注损伤对大鼠心肌中氨基酸的影响及牛磺酸的保护作用

使用大鼠离体作功心脏缺血一再灌注损伤模型,观察心肌内游离氨基酸含量的变化以及牛磺酸(Taurine,Tau)对心脏的影响.发现再灌注损伤使心肌内所测17种游离氨基酸含量除Cys外部减少,其中Tau降低最显著.20 mmol·L~(-1)Tau能改善心脏的再灌注损伤,表现为:在再灌注期间促进心脏机械功能的恢复,减少室性心律失常的发生率,减少LDH与CK从心肌中漏出,减少脂质过氧化作用与钙的积聚以及减少心肌内游离氨基酸的丢失.提示:外源性Tau能够改善心脏的缺血一再灌注损伤.