Sodium removal and sodium concentration during peritoneal dialysis: effects of three methods of sodium measurement.

BACKGROUND: Sodium removal (NaR) may have a major impact on the survival of peritoneal dialysis patients. The dialysate/plasma sodium concentration ratio (D/P(Na)) is an indirect index of transcellular water transport by aquaporin channels, and thus of ultrafiltration. Sodium concentration can be assessed by means of flame photometry (F), and direct (D-ISE) or indirect ion-selective electrodes (I-ISE), but these methods have different properties. I-ISE is being used increasingly in clinical laboratories. The aim of this study was to evaluate NaR and D/P(Na) using the three different measurement methods. METHODS: We performed peritoneal equilibration tests (PETs) in 44 peritoneal dialysis patients and calculated the NaR. We also calculated D/P(Na) during the test; plasma and dialysate sodium concentrations were measured by F, D-ISE and I-ISE. RESULTS: NaR was lower (P<0.001) with D-ISE (69+/-29 mmol) than with F (81+/-29 mmol) or I-ISE (79+/-28 mmol). D/P(Na) was also lower at baseline (0.92+/-0.02 vs 0.95+/-0.02 and 0.95+/-0.02; P<0.001), after 60 min (0.87+/-0.03 vs 0.90+/-0.03 and 0.90+/-0.03; P<0.001) and at the end of PET (0.88+/-0.04 vs 0.92+/-0.04 and 0.92+/-0.04; P<0.001) when measured by D-ISE in comparison with F and I-ISE, respectively. CONCLUSIONS: NaR and D/P(Na) were lower when measured by the D-ISE method compared with the F and I-ISE methods. NaR and D/P(Na) were similar when measured by F or I-ISE. I-ISE can be used reliably in the evaluation of NaR and D/P(Na) in everyday clinical practice of peritoneal dialysis.     

Autonomic Regulation of Voltage-Gated Cardiac Ion Channels

Altering voltage-gated ion channel currents, by changing channel number or voltage-dependent kinetics, regulates the propagation of action potentials along the plasma membrane of individual cells and from one cell to its neighbors. Functional increases in the number of cardiac sodium channels (Na_V1.5) at the myocardial sarcolemma are accomplished by the regulation of caveolae by β adrenergically stimulated G-proteins. We demonstrate that Na_V1.5, Ca_V1.2a, and K_V1.5 channels specifically localize to isolated caveolar membranes, and to punctate regions of the sarcolemma labeled with caveolin-3. In addition, we show that Na_V1.5, Ca_V1.2a, and K_V1.5 channel antibodies label the same subpopulation of isolated caveolae. Plasma membrane sheet assays demonstrate that Na_V1.5, Ca_V1.2a, and K_V1.5 cluster with caveolin-3. This may have interesting implications for the way in which adrenergic pathways alter the cardiac action potential morphology and the velocity of the excitatory wave.     

The effect of sodium lauryl sulphate on the expression of cytokeratin mRNA in hamster cheek pouch epithelium

The effect of sodium lauryl sulphate (SLS) on cytokeratin (CK) gene expression in hamster cheek pouch epithelium was studied with a hybridohistochemical technique. Using specific human anti-sense RNA probes, the plausible hamster mRNA counterparts for these human CK mRNAs were localized by detection of heterologous hybrids. In comparison with normal epithelium, the expression and distribution pattern of CK mRNAs in the hamster cheek pouch were obviously changed after application of SLS. There was a decreased expression of CK mRNAs in the hyperplastic basal layer, and increased expression in the hypertrophic granular layer. Strikingly, hybridization with the human CK 18 cRNA probe revealed an additionally expressed CK mRNA in the SLS-treated epithelium that was not found in the untreated epithelium. The present study indicates that cRNA probes for human CK mRNAs can be used successfully, not only to distinguish between different hamster CK mRNAs but also to investigate changes in CK gene expression upon the induction of non-neoplastic and neoplastic alterations in the hamster cheek pouch model. This may help elucidate the molecular changes involved in epithelial pathologies.     

Reduction in sodium chloride intake: effects on urinary Na, K and aldosterone output in healthy free-living adults

Eleven healthy free-living adults (six women, five men) weighed and recorded all food and drink consumed and collected all urine for two non-consecutive 7-day periods whilst eating their usual diet (Period 1) and attempting to reduce salt intake (Period 2). Bread (including pitta bread) provided on average a quarter of total Na intake of subjects in Period 1 so that wholemeal bread made without added salt was made available in Period 2. All subjects achieved substantial reductions (mean 65%) in Na intake in Period 2 with no change in K intake so that the Na:K molar ratio fell from 1.3 to 0.5. Urinary Na output closely followed intakes and there was a large increase (mean 11.2 μg/d) in aldosterone excretion with a non-significant increase in K output. Simple linear relationships which allow prediction of Na and K intake from the more easily measured urinary output were derived.     

Effects of topical anti-inflammatory drugs on eosinophil survival primed by epithelial cells. Additive effect of glucocorticoids and nedocromil sodium

Background Eosinophil infiltration is a hallmark of the inflammatory response in rhinitis and in nasal polypcsis. Objective We studied the effect of steroids and nedocromil sodium on eosinophil survival primed by epithelial cells from healthy (nasal mucosa) and inflamed (nasal polyp) respiratory tissue. Methods Blood eosinophils were incubated with increasing concentrations (10^-11 10^-5 M) of topical steroids (fiuticasone propionate, budesonide, triamcinolone acetonide and beclomethasone dipropionate) and/or nedocromil sodium prior to the addition of human epithelial cell conditioned media (HECM), eosinophil viability was measured and IC₅₀ for each drug was calculated. Results All four steroids and nedocromil sodium caused a dose-related inhibition of HECM-induced eosinophil survival. The IC₅₀ of steroids were lower in eosinophils primed by mucosa HECM than on those primed by polyp HECM (fluticasone, 4nM vs 114nM: budesonide, 21 nM vs 280 nM; triamcinolone, 7 nM vs 853 nM; and beclomethasone, 171 nM vs 181 nM). The combined inhibitory effect of 10^-7M budesonide plus 10^-5M nedocromil (43.8 ± 10.8%, P < 0.03) was significantly higher than budesonide (28.5 ± 9.2%) or nedocromil (16.7 ± 5.4%) alone and close to 10^-5M budesonide (52.3 ± 11%). No differences were found in cytokine (IL-8, IL-6, GM-CSF, TNFα, IL-lβ and RANTES) concentrations between HECM from mucosa and polyps. Conclusion These results suggest that topical anti-inflammatory drugs may diminish airway eosinophilic infiltration by decreasing eosinophil viability, that nasal polyp epithelial cell secretions may induce steroid resistance in eosinophils, and that nedocromil sodium has additive effects with steroids.     

呋苄青霉素药代动力学及组织分布的研究

呋苄青霉素是由我国开发成功的一个酰脲类青霉素。本项研究采用微生物法,以狗和正常人为受试对象,以氧哌嗪青霉素和羧苄青霉素为对照进行药代动力学研究,结果表明,3个药的药—时曲线符合二室开放式模型,呋苄青霉素较其它对照药具较高的即刻血浓度和较低的肾清除率。用微生物法和放射自显影法测定的呋苄青霉素在小鼠体内组织分布汪明,呋苄青霉素广泛分布于体内各组织,尤其在肺、肝、肠中的浓度明显高于羧苄青霉素。     

NaFeEDTA预防大鼠铅中毒的研究及其对锌、铜的影响

为探讨乙二胺四乙酸铁钠 (NaFeEDTA)在预防大鼠铅中毒及减低铅毒性中的作用 ,同时研究其对锌、铜二元素的影响 ,采用随机分组的动物实验设计方法 ,将 60只Wistar大鼠随机分为空白对照组、模型对照组、阳性药物组和高、中、低NaFeEDTA组 ,共 6组 ,除空白对照组外 ,对其余各组大鼠进行持续性染铅 ,而且除模型对照组外的 4个染铅组分别同时给予二巯基丁二酸 (DMSA)、高、中、低浓度的NaFeEDTA溶液。 5周后实验结束 ,对相关指标进行测定。结果显示 ,三个NaFeEDTA组的血红蛋白含量均显著高于其它各组 ,同时其血铅、脑铅、肝脏铅、肾脏铅及胫骨铅含量显著低于模型对照组 ,而且它们的肝脏铅、肾脏铅和胫骨铅含量与每日每只大鼠铁补充量之间存在显著负相关 ,相关系数分别为 - 0 4432、- 0 61 34和 - 0 3878;除中、高浓度NaFeEDTA组的脑锌水平低于模型对照组以及低浓度NaFeEDTA组的肾脏铜含量高于模型对照组外 ,其余各NaFeEDTA组的脏器锌、铜含量与模型对照组相比均无显著性差异。提示NaFeEDTA可有效提高大鼠的血红蛋白含量 ,能够预防大鼠铅中毒 ,减低铅对大鼠的毒性作用 ;同时对体内锌、铜含量无太大影响     

复合膳食纤维对大鼠体内脂质过氧化作用的影响

制备复合膳食纤维 (dietaryfiber,DF) ,并分别探讨复合、混合及三种单一的DF对高脂血症大鼠体内脂质过氧化作用的影响。选健康、断乳Wistar大鼠 6 4只 ,按体重随机分为 8组 ,用高脂饲料诱发高脂血症的同时 ,分别添加 10 %的DF :纤维素 (B组 )、果胶 (C组 )、海藻酸钠 (D组 )、纤维素 -果胶复合物 (E组 )、纤维素 -海藻酸钠复合物 (F组 )、纤维素 -果胶混合物 (G组 )、纤维素 -海藻酸钠混合物 (H组 ) ,以单纯的高脂饲料组为对照组 (A组 ) ,观察各种DF对大鼠的生长发育及脂质过氧化作用的影响。结果显示 :1、添加 10 %的各种DF不影响大鼠的生长发育。 2、各种DF皆可显著升高血清超氧化物歧化酶 (SOD) (P <0 0 1)、谷胱甘肽过氧化物酶 (GSH Px)活性 (P <0 0 1) ,降低丙二醛 (MDA)水平 (P <0 0 5 ,B、D组除外 ) ,提高红细胞膜的流动性 (P <0 0 5 ) ,以复合物、混合物效果为明显。 3、各种DF可不同程度地增加粪重和粪脂排出量 (P <0 0 5 ,D组除外 ) ,以复合物、混合物为明显。提示各种DF皆可不同程度地降低大鼠体内脂质过氧化作用 ,提高红细胞膜的流动性 ,其中可溶性DF效果优于不可溶性DF ,而复合、混合DF的效果又优于单一的DF ,且以复合物效果为佳