Cardiac mitochondrial damage and biogenesis in a chronic model of type 1 diabetes

Diabetic cardiomyopathy is a common complication leading to heightened risk of heart failure and death. In the present report, we performed proteomic analysis on total cardiac proteins from the OVE26 mouse model of type 1 diabetes to identify protein changes that may contribute to diabetic cardiomyopathy. This analysis revealed that a surprising high proportion (12 of 20) of the altered proteins that could be identified by mass spectrometry were of mitochondrial origin. All but one of these proteins were upregulated by diabetes. Quantitative RT-PCR, performed for two of these proteins, indicated that part of the upregulation was attributed to increased messenger RNA levels. Morphological study of diabetic hearts showed significantly increased mitochondrial area and number as well as focal regions with severe damage to mitochondria. Diabetic mitochondria also showed reduced respiratory control ratio (9.63 +/- 0.20 vs. 6.13 +/- 0.41, P < 0.0001), apparently due to reduced state 3 rate, and diminished GSH level (5.5 +/- 0.9 vs. 8.2 +/- 2.5 micromol/mg protein, P < 0.05), indicating impaired mitochondrial function and increased oxidative stress. Further examination revealed increased mitochondrial DNA (1.03 +/- 0.18 vs. 0.69 +/- 0.13 relative copy number, P < 0.001) and a tendency to higher protein yield in OVE26 cardiac mitochondria, as well as increased mRNA level for mitochondrial transcription factor A and two mitochondrial encoded proteins. Taken together, these results show that mitochondria are a primary target in the diabetic heart, probably due to oxidative stress, and that this damage coincides with and may stimulate mitochondrial biogenesis.

Quantitative proteomics analysis of specific protein expression and oxidative modification in aged senescence-accelerated-prone 8 mice brain

The senescence-accelerated mouse (SAM) is a murine model of accelerated senescence that was established using phenotypic selection. The SAMP series includes nine substrains, each of which exhibits characteristic disorders. SAMP8 is known to exhibit age-dependent learning and memory deficits. In our previous study, we reported that brains from 12-month-old SAMP8 have greater protein oxidation, as well as lipid peroxidation, compared with brains from 4-month-old SAMP8 mice. In order to investigate the relation between age-associated oxidative stress on specific protein oxidation and age-related learning and memory deficits in SAMP8, we used proteomics to identify proteins that are expressed differently and/or modified oxidatively in aged SAMP8 brains. We report here that in 12 month SAMP8 mice brains the expressions of neurofilament triplet L protein, lactate dehydrogenase 2 (LDH-2), heat shock protein 86, and alpha-spectrin are significantly decreased, while the expression of triosephosphate isomerase (TPI) is increased compared with 4-month-old SAMP8 brains. We also report that the specific protein carbonyl levels of LDH-2, dihydropyrimidinase-like protein 2, alpha-spectrin and creatine kinase, are significantly increased in the brain of 12-month-old SAMP8 mice when compared with the 4-month-old SAMP8 brain. These findings are discussed in reference to the effect of specific protein oxidation and changes of expression on potential mechanisms of abnormal alterations in metabolism and neurochemicals, as well as to the learning and memory deficits in aged SAMP8 mice.

Alterations in the renal elastin-elastase system in type 1 diabetic nephropathy identified by proteomic analysis

Diabetes now accounts for >40% of patients with ESRD. Despite significant progress in understanding diabetic nephropathy, the cellular mechanisms that lead to diabetes-induced renal damage are incompletely defined. For defining changes in protein expression that accompany diabetic nephropathy, the renal proteome of 120-d-old OVE26 transgenic mice with hypoinsulinemia, hyperglycemia, hyperlipidemia, and proteinuria were compared with those of background FVB nondiabetic mice (n = 5). Proteins derived from whole-kidney lysate were separated by two-dimensional PAGE and identified by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry. Forty-one proteins from 300 visualized protein spots were differentially expressed in diabetic kidneys. Among these altered proteins, expression of monocyte/neutrophil elastase inhibitor was increased, whereas elastase IIIB was decreased, leading to the hypothesis that elastin expression would be increased in diabetic kidneys. Renal immunohistochemistry for elastin of 325-d-old FVB and OVE26 mice demonstrated marked accumulation of elastin in the macula densa, collecting ducts, and pelvicalyceal epithelia of diabetic kidneys. Elastin immunohistochemistry of human renal biopsies from patients with type 1 diabetes (n = 3) showed increased elastin expression in renal tubular cells and the interstitium but not glomeruli. These results suggest that coordinated changes in elastase inhibitor and elastase expression result in increased tubulointerstitial deposition of elastin in diabetic nephropathy. The identification of these coordinated changes in protein expression in diabetic nephropathy indicates the potential value of proteomic analysis in defining pathophysiology.

Proteomics in nephrology: current status and future directions

Proteomics is one among various 'OMICS' fields that have been growing rapidly in the postgenomic era. During the past few years, proteomics has been extensively applied to several fields of medicine to better understand normal physiology, to define the pathophysiology of diseases, and to identify novel biomarkers and new therapeutic targets. This review focuses on current status and future directions of proteomics in the nephrology field. Recent studies of renal proteome, proteomes of individual intrarenal structures (i.e., glomerular, vascular, tubular, brush border membrane, mesangial, and podocyte proteomes), urinary proteome, and protein profiles in dialysate or ultrafiltrate removed by renal replacement therapy are summarized.

Proteomic analysis of brain proteins in the gracile axonal dystrophy (gad) mouse, a syndrome that emanates from dysfunctional ubiquitin carboxyl-terminal hydrolase L-1, reveals oxidation of key proteins

Ubiquitin carboxyl-terminal hydrolase L-1 (UCH L-1) is a crucial enzyme for proteasomal protein degradation that generates free monomeric ubiquitin. Our previous proteomic study identified UCH L-1 as one specific target of protein oxidation in Alzheimer's disease (AD) brain, establishing a link between the effect of oxidative stress on protein and the proteasomal dysfunction in AD. However, it is unclear how protein oxidation affects function, owing to the different responses of proteins to oxidation. Analysis of systems in which the oxidized protein displays lowered or null activity might be an excellent model for investigating the effect of the protein of interest in cellular metabolism and evaluating how the cell responds to the stress caused by oxidation of a specific protein. The gracile axonal dystrophy (gad) mouse is an autosomal recessive spontaneous mutant with a deletion on chromosome 5 within the gene encoding UCH L-1. The mouse displays axonal degeneration of the gracile tract. The aim of this proteomic study on gad mouse brain, with dysfunctional UCH L-1, was to determine differences in brain protein oxidation levels between control and gad samples. The results showed increased protein oxidation in thioredoxin peroxidase (peroxiredoxin), phosphoglycerate mutase, Rab GDP dissociation inhibitor alpha/ATP synthase and neurofilament-L in the gad mouse brain. These findings are discussed with reference to the effect of specific protein oxidation on potential mechanisms of neurodegeneration that pertain to the gad mouse.

Proteomic identification of a novel protein regulated in CA1 and CA3 hippocampal regions during intermittent hypoxia

The CA1 and CA3 regions of the hippocampus markedly differ in their susceptibility to hypoxia in general, and more particularly to the intermittent hypoxia (IH) that characterizes sleep apnea. We used proteomic analysis to build a database of proteins expressed in normoxic CA1 and CA3. The current hippocampus protein database identifies 106 proteins. A hypothetical protein with accession number AK006737 (gimid R:12839969) was strongly upregulated in the CA1, but not CA3 hippocampal region. Bioinformatic analysis revealed that the unknown protein contained a high stringency protein kinase e binding site. Domain analysis demonstrated the presence of a conserved sequence indicative of macrophage scavenger receptors. Using proteomic analysis we have previously demonstrated that acute (6 h) IH-mediated CA1 injury results from complex interactions between pathways involving increased metabolism, induction of stress-induced proteins and apoptosis, and ultimately disruption of structural proteins and cell integrity. The current findings identify a hypothetical protein that may play a key role in the response of CA1 to IH. These findings provide initial insights into mechanisms underlying differences in susceptibility to hypoxia in neural tissue and demonstrate how proteomic analysis can be used to generate new hypotheses, which define neuronal adaptation to IH.

Sodium loading changes urinary protein excretion: a proteomic analysis

Plasma sodium concentration is maintained even when sodium intake is altered. Sodium homeostasis may involve changes in renal tubular protein expression that are reflected in the urine. We used proteomic analysis to investigate changes in urinary protein excretion in response to acute sodium loading. Rats were given deionized water followed by hypertonic (2.7%) saline for 28 h each. Urinary protein expression was determined during the final 4 h of each treatment. Acute sodium loading increased urinary sodium excretion (4.53 +/- 1.74 vs. 1.70 +/- 0.27 mmol/day, P = 0.029). Urinary proteins were separated by two-dimensional PAGE and visualized by Sypro ruby staining. Differentially expressed proteins were identified by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry followed by peptide mass fingerprinting. The abundance of a total of 45 protein components was changed after acute sodium loading. Neutral endopeptidase, solute carrier family 3, meprin 1alpha, diphor-1, chaperone heat shock protein 72, vacuolar H(+)-ATPase, ezrin, ezrin/radixin/moesin-binding protein, glutamine synthetase, guanine nucleotide-binding protein, Rho GDI-1, and chloride intracellular channel protein 1 were decreased, whereas albumin and alpha-2u globulin were increased. Some of these proteins have previously been shown to be associated with tubular transport. These data indicate that alterations in the excretion of several urinary proteins occur during acute sodium loading.

Proteomic identification of nitrated proteins in Alzheimer's disease brain

Nitration of tyrosine in biological conditions represents a pathological event that is associated with several neurodegenerative diseases, such as amyotrophic lateral sclerosis, Parkinson's disease and Alzheimer's disease (AD). Increased levels of nitrated proteins have been reported in AD brain and CSF, demonstrating the potential involvement of reactive nitrogen species (RNS) in neurodegeneration associated with this disease. Reaction of NO with O2- leads to formation of peroxynitrite ONOO-, which following protonation, generates cytotoxic species that oxidize and nitrate proteins. Several findings suggest an important role of protein nitration in modulating the activity of key enzymes in neurodegenerative disorders, although extensive studies on specific targets of protein nitration in disease are still missing. The present investigation represents a further step in understanding the relationship between oxidative modification of protein and neuronal death in AD. We previously applied a proteomics approach to determine specific targets of protein oxidation in AD brain, by successfully coupling immunochemical detection of protein carbonyls with two-dimensional polyacrylamide gel electrophoresis and mass spectrometry analysis. In the present study, we extend our investigation of protein oxidative modification in AD brain to targets of protein nitration. The identification of six targets of protein nitration in AD brain provides evidence to the importance of oxidative stress in the progression of this dementing disease and potentially establishes a link between RNS-related protein modification and neurodegeneration.

Protein kinase C-dependent phosphorylation and mitochondrial translocation of aldose reductase

Although aldose reductase (AR) is a critical participant in osmoregulation, and the metabolism of glucose and aldehydes derived from lipid peroxidation, post-translational mechanisms regulating its activity have not been identified. In this paper, we report that stimulation of protein kinase C (PKC) in several cell types induces phosphorylation of AR and translocation of the phosphorylated protein to the mitochondria. In vitro, recombinant AR was directly phosphorylated by activated PKC, suggesting that AR may be an in vivo PKC substrate. Together, these observations reveal a novel link between PKC activation and the regulation of glucose and aldehyde metabolism.

Practical Bioinformatics for Proteomics

We used various bioinformatic tools to examine the unknown protein gi|12841975 that was up-regulated in mouse diabetic kidneys. The data indicate that this unknown protein is, indeed, the PEBP. Motif scanning showed that this protein contains several kinase motifs, especially PKC that plays an important role in the pathogenesis of diabetic nephropathy [24, 25]. We therefore hypothesize that this protein (PEBP) has a potential functional role in PKC-dependent pathogenic pathways of diabetic nephropathy. Further study will be focused on phosphorylation pathways of the PEBP and its substrates. In summary, we have presented a case study that outlines our approach to further characterize the unknown proteins identified by peptide mass fingerprinting. Publicly accessible bioinformatic tools can provide a wealth of information to guide subsequent approaches that use traditional molecular biology tools.

Differential expression of proteins in renal cortex and medulla: a proteomic approach

BACKGROUND

Western blotting has previously been used to identify changes in protein expression in renal tissue. However, only a few proteins can be studied in each experiment by Western blot. We have used proteomic tools to construct protein maps of rat kidney cortex and medulla.

METHODS

Expression of proteins was determined by silver stain after two-dimensional polyacrylamide gel electrophoresis (2D-PAGE). Protein spots were excised and digested with trypsin. Peptide masses were identified by MALDI-TOF mass spectrometry. The Mascot search engine was used to analyze the peptide masses and identify the proteins.

RESULTS

Seventy-two proteins were identified (54 unique proteins) out of approximately 1000 spots visualized on each gel. Most of the spots were expressed both in cortex and medulla. Of the identified proteins, three were expressed only in medulla and one only in cortex. Nine proteins were expressed in both regions but to a greater extent in cortex and three proteins were expressed more in medulla. Differential expression was confirmed for three proteins by Western blot.

CONCLUSIONS

A large group of proteins and their relative expression levels from cortical and medullary portions of rat kidneys were found. Sixteen proteins are differentially expressed. Proteomics can be used to identify differential expression of proteins in the kidney on a large scale. Proteomics should be useful to detect changes in renal protein expression in response to a large range of physiological and pathophysiological stimuli.

Proteomic analysis of normal human urinary proteins isolated by acetone precipitation or ultracentrifugation

BACKGROUND

Proteomic techniques have recently become available for large-scale protein analysis. The utility of these techniques in identification of urinary proteins is poorly defined. We constructed a proteome map of normal human urine as a reference protein database by using two differential fractionated techniques to isolate the proteins.

METHODS

Proteins were isolated from urine obtained from normal human volunteers by acetone precipitation or ultracentrifugation, separated by two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) and identified by matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) mass spectrometry followed by peptide mass fingerprinting.

RESULTS

A total of 67 protein forms of 47 unique proteins were identified, including transporters, adhesion molecules, complement, chaperones, receptors, enzymes, serpins, cell signaling proteins and matrix proteins. Acetone precipitated more acidic and hydrophilic proteins, whereas ultracentrifugation fractionated more basic, hydrophobic, and membrane proteins. Bioinformatic analysis predicted glycosylation to be the most common explanation for multiple forms of the same protein.

CONCLUSIONS

Combining two differential isolation techniques magnified protein identification from human urine. Proteomic analysis of urinary proteins is a promising tool to study renal physiology and pathophysiology and to determine biomarkers of renal disease.

Proteomic analysis of CA1 and CA3 regions of rat hippocampus and differential susceptibility to intermittent hypoxia

The CA1 and CA3 regions of the hippocampus markedly differ in their susceptibility to hypoxia in general, and more particularly to the intermittent hypoxia that characterizes sleep apnea. Proteomic approaches were used to identify proteins differentially expressed in the CA1 and CA3 regions of the rat hippocampus and to assess changes in protein expression following a 6-h exposure to intermittent hypoxia (IH). Ninety-nine proteins were identified, and 15 were differentially expressed in the CA1 and the CA3 regions. Following IH, 32 proteins in the CA1 region and only 7 proteins in the more resistant CA3 area were up-regulated. Hypoxia-regulated proteins in the CA1 region included structural proteins, proteins related to apoptosis, primarily chaperone proteins, and proteins involved in cellular metabolic pathways. We conclude that IH-mediated CA1 injury results from complex interactions between pathways involving increased metabolism, induction of stress-induced proteins and apoptosis, and, ultimately, disruption of structural proteins and cell integrity. These findings provide initial insights into mechanisms underlying differences in susceptibility to hypoxia in neural tissue, and may allow for future delineation of interventional strategies aiming to enhance neuronal adaptation to IH.

Proteomic analysis reveals alterations in the renal kallikrein pathway during hypoxia-induced hypertension

Obstructive sleep apnea syndrome (OSAS), a disorder characterized by episodic hypoxia (EH) during sleep, is associated with systemic hypertension. We used proteomic analysis to examine differences in rat kidney protein expression during EH, and their potential relationship to EH-induced hypertension. Young male Sprague-Dawley rats were exposed to either EH or sustained hypoxia (SH) for 14 (EH14/SH14) and 30 (EH30/SH30) days. Mean arterial blood pressure was significantly increased only in EH30 (p < 0.0002). Kidney proteins were resolved by two-dimensional-PAGE and were identified by MALDI-MS. Renal expression of kallistatin, a potent vasodilator, was down-regulated in all animals. Expression of alpha-1-antitrypsin, an inhibitor of kallikrein activation, was up-regulated in EH but down-regulated in SH. Western blotting showed significant elevation of B(2)-bradykinin receptor expression in all normotensive animals but remained unchanged in hypertensive animals. Proteins relevant to vascular hypertrophy, such as smooth muscle myosin and protein-disulfide isomerase were up-regulated in EH30 but were down-regulated in SH30. These data indicate that EH induces changes in renal protein expression consistent with impairment of vasodilation mediated by the kallikrein-kallistatin pathway and vascular hypertrophy. In contrast, SH-induced changes suggest the kallikrein- and bradykinin-mediated compensatory mechanisms for prevention of hypertension and vascular remodeling. To test the hypothesis suggested by the proteomic data, we measured the effect of EH on blood pressure in transgenic hKLK1 rats that overexpress human kallikrein. Transgenic hKLK1 animals were protected from EH-induced hypertension. We conclude that EH-induced hypertension may result, at least in part, from altered regulation of the renal kallikrein system.

Proteomic identification of oxidatively modified proteins in Alzheimer's disease brain. Part II: dihydropyrimidinase-related protein 2, alpha-enolase and heat shock cognate 71

Alzheimer's disease (AD) is a neurodegenerative disorder in which oxidative stress has been implicated as an important event in the progression of the pathology. In particular, it has been shown that protein modification by reactive oxygen species (ROS) occurs to a greater extent in AD than in control brain, suggesting a possible role for oxidation-related decrease in protein function in the process of neurodegeneration. Oxidative damage to proteins, assessed by measuring the protein carbonyl content, is involved in several events such as loss in specific protein function, abnormal protein clearance, depletion of the cellular redox-balance and interference with the cell cycle, and, ultimately, neuronal death. The present investigation represents a further step in understanding the relationship between oxidative modification of protein and neuronal death in AD. Previously, we used our proteomics approach, which successfully substitutes for labor-intensive immunochemical analysis, to detect proteins and identified creatine kinase, glutamine synthase and ubiquitin carboxy-terminal hydrolase L-1 as specifically oxidized proteins in AD brain. In this report we again applied our proteomics approach to identify new targets of protein oxidation in AD inferior parietal lobe (IPL). The dihydropyrimidinase related protein 2 (DRP-2), which is involved in the axonal growth and guidance, showed significantly increased level in protein carbonyls in AD brain, suggesting a role for impaired mechanism of neural network formation in AD. Additionally, the cytosolic enzyme alpha-enolase was identified as a target of protein oxidation and is involved the glycolytic pathway in the pathological events of AD. Finally, the heat shock cognate 71 (HSC-71) revealed increased, but not significant, oxidation in AD brain. These results are discussed with reference to potential involvement of these oxidatively modified proteins in neurodegeneration in AD brain.

Proteomic identification of oxidatively modified proteins in Alzheimer's disease brain. Part I: creatine kinase BB, glutamine synthase, and ubiquitin carboxy-terminal hydrolase L-1

Oxidative alterations of proteins by reactive oxygen species (ROS) have been implicated in the progression of aging and age-related neurodegenerative disorders such as Alzheimer's disease (AD). Protein carbonyls, a marker of protein oxidation, are increased in AD brain, indicating that oxidative modification of proteins is relevant in AD. Oxidative damage can lead to several events such as loss in specific protein function, abnormal protein clearance, depletion of the cellular redox-balance and interference with the cell cycle, and, ultimately, to neuronal death. Identification of specific targets of protein oxidation represents a crucial step in establishing a relationship between oxidative modification and neuronal death in AD, and was partially achieved previously in our laboratory through immunochemical detection of creatine kinase BB and beta-actin as specifically oxidized proteins in AD brain versus control brain. However, this process is laborious, requires the availability of specific antibodies, and, most importantly, requires a reasonable guess as to the identity of the protein in the first place. In this study, we present the first proteomics approach to identify specifically oxidized proteins in AD, by coupling 2D fingerprinting with immunological detection of carbonyls and identification of proteins by mass spectrometry. The powerful techniques, emerging from application of proteomics to neurodegenerative disease, reveal the presence of specific targets of protein oxidation in Alzheimer's disease (AD) brain: creatine kinase BB, glutamine synthase, and ubiquitin carboxy-terminal hydrolase L-1. These results are discussed with reference to potential involvement of these oxidatively modified proteins in neurodegeneration in AD brain. Proteomics offers a rapid means of identifying oxidatively modified proteins in aging and age-related neurodegenerative disorders without the limitations of the immunochemical detection method.

Fluoride exposure attenuates expression of Streptococcus pyogenes virulence factors

Fluoridation causes an obvious reduction of dental caries by interference with cariogenic streptococci. However, the effect of fluoride on group A streptococci that causes rheumatic fever and acute poststreptococcal glomerulonephritis is not known. We have used proteomic analysis to create a reference proteome map for Streptococcus pyogenes and to determine fluoride-induced protein changes in the streptococci. Cellular and extracellular proteins were resolved by two-dimensional polyacrylamide gel electrophoresis and identified by matrix-assisted laser desorption ionization mass spectrometry. 183 protein spots were visualized, and 74 spots representing 60 unique proteins were identified. A 16-h exposure to sodium fluoride caused decreased expression of proteins required to respond to cellular stress, including anti-oxidants, glycolytic enzymes, transcriptional and translational regulators, and protein folding. Fluoride caused decreased cellular expression of two well-characterized S. pyogenes virulence factors. Fluoride decreased expression of glyceraldehyde-3-phosphate dehydrogenase, which acts to bind fibronectin and promote bacterial adherence. We also performed proteomic analysis of protein released by S. pyogenes into the culture supernatant and observed decreased expression of M proteins following fluoride exposure. These data provide evidence that fluoride causes decreased expression by S. pyogenes proteins used to respond to stress, virulence factors, and implicated in non-suppurative complications of S. pyogenes, including glomerulonephritis and rheumatic fever.

Better correction of metabolic acidosis, blood pressure control, and phagocytosis with bicarbonate compared to lactate solution in acute peritoneal dialysis

Lactate solution has been the standard dialysate fluid for a long time. However, it tends to convert back into lactic acid in poor tissue-perfusion states. The aim of this study was to evaluate the efficacy of magnesium (Mg)- and calcium (Ca)-free bicarbonate solution compared with lactate solution in acute peritoneal dialysis (PD). Renal failure patients who were indicated for dialysis and needed acute PD were classified as shock and nonshock groups, and then were randomized to receive either bicarbonate or lactate solution. Twenty patients were enrolled in this study (5 in each subgroup). In the shock group, there were more rapid improvements and significantly higher levels of blood pH (7.40 +/- 0.04 versus 7.28 +/- 0.05, p < 0.05), serum bicarbonate (23.30 +/- 1.46 versus 18.37 +/- 1.25 mmol/L, p < 0.05), systolic pressure (106.80 +/- 3.68 versus 97.44 +/- 3.94 mm Hg, p < 0.05), mean arterial pressure (80.72 +/- 2.01 versus 73.28 +/- 2.41 mm Hg, p < 0.05), percentages of phagocytosis of circulating leukocytes (65.85% +/- 2.22 versus 52.12% +/- 2.71, p < 0.05), and percentages of positive nitroblue tetrazolium (NBT) reduction test without and with stimulation (14.43 +/- 1.93 versus 9.43 +/- 2.12, p < 0.05 and 65.08 +/- 6.80 versus 50.23 +/- 4.21, p < 0.05, respectively) in the bicarbonate subgroup compared with the lactate subgroup. In the nonshock group, blood pH, serum bicarbonate, and phagocytosis assays in both subgroups were comparable. Lactic acidosis was more rapidly recovered and was significantly lower with bicarbonate solution for both shock and nonshock groups (3.63 +/- 0.37 versus 5.21 +/- 0.30 mmol/L, p < 0.05 and 2.92 +/- 0.40 versus 3.44 +/- 0.34 mmol/L, p < 0.05, respectively). Peritoneal urea and creatinine clearances in both subgroups were comparable for both shock and nonshock groups. There was no peritonitis observed during the study. Serum Mg and Ca levels in the bicarbonate subgroup were significantly lower, but no clinical and electrocardiographic abnormality were observed. We concluded that Mg- and Ca-free bicarbonate solution could be safely used and had better outcomes in correction of metabolic acidosis, blood pressure control, and nonspecific systemic host defense with comparable efficacy when compared to lactate solution. It should be the dialysate of choice for acute PD especially in the poor tissue-perfusion states such as shock, lactic acidosis, and multiple organ failure.