A Gγ protein regulates alkaline sensitivity in crops.

The use of alkaline salt lands for crop production is hindered by a scarcity of knowledge and breeding efforts for plant alkaline tolerance. Through genome association analysis of sorghum, a naturally high-alkaline-tolerant crop, we detected a major locus, Alkaline Tolerance 1 (AT1), specifically related to alkaline-salinity sensitivity. An at1 allele with a carboxyl-terminal truncation increased sensitivity, whereas knockout of AT1 increased tolerance to alkalinity in sorghum, millet, rice, and maize. AT1 encodes an atypical G protein γ subunit that affects the phosphorylation of aquaporins to modulate the distribution of hydrogen peroxide (H2O2). These processes appear to protect plants against oxidative stress by alkali. Designing knockouts of AT1 homologs or selecting its natural nonfunctional alleles could improve crop productivity in sodic lands.

Determinants of hypokalemia following hypertonic sodium bicarbonate infusion.

The hypokalemic response to alkali infusion has been attributed to the resulting extracellular fluid (ECF) expansion, urinary potassium excretion, and internal potassium shifts, but the dominant mechanism remains uncertain. Hypertonic NaHCO3 infusion (1 N, 5 mmol/kg) to unanesthetized dogs with normal acid-base status or one of the four chronic acid-base disorders decreased plasma potassium concentration ([K+]p) at 30 min in all study groups (Δ[K+]p, - 0.16 to - 0.73 mmol/L), which remained essentially unaltered up to 90-min postinfusion. ECF expansion accounted for only a small fraction of the decrease in ECF potassium content, (K+)e. Urinary potassium losses were large in normals and chronic respiratory acid-base disorders, limited in chronic metabolic alkalosis, and minimal in chronic metabolic acidosis, yet, ongoing kaliuresis did not impact the stability of [K+]p. All five groups experienced a reduction in (K+)e at 30-min postinfusion, Δ(K+)e remaining unchanged thereafter. Intracellular fluid (ICF) potassium content, (K+)i, decreased progressively postinfusion in all groups excluding chronic metabolic acidosis, in which a reduction in (K+)e was accompanied by an increase in (K+)i. We demonstrate that hypokalemia following hypertonic NaHCO3 infusion in intact animals with acidemia, alkalemia, or normal acid-base status and intact or depleted potassium stores is critically dependent on mechanisms of internal potassium balance and not ECF volume expansion or kaliuresis. We envision that the acute NaHCO3 infusion elicits immediate ionic shifts between ECF and ICF leading to hypokalemia. Thereafter, maintenance of a relatively stable, although depressed, [K+]e requires that cells release potassium to counterbalance ongoing urinary potassium losses.

Physiological and proteomics responses of nitrogen assimilation and glutamine/glutamine family of amino acids metabolism in mulberry (Morus alba L.) leaves to NaCl and NaHCO3 stress.

In order to find out the response mechanism of nitrogen assimilation and glutamine/glutamine family of amino acids metabolism in mulberry (Morus alba L.) leaves under NaCl and NaHCO3 stress, and to reveal its role in salt alkali adaptation. The effects of the nitrogen metabolism of mulberry leaves were studied under 100 mmol L-1 NaCl and NaHCO3 stress.The results showed that the activity of NR and the content of TN and SP did not change significantly, the expression of NiR, Fd-NiR, Fd-NiR gene and theactivity of NiR increased significantly under NaCl stress, but nitrogen assimilation was inhibited under NaHCO3 stress. NaCl stress had no significant effect on the expression and activity of GS and GOGAT in mulberry leaves. Under NaHCO3 stress, the expression of Fd-GOGAT, Fd-GOGAT2, Fd-GOGAT gene, and the activity of GS and GOGAT were significantly decreased. NaCl stress can promote the accumulation of Pro, Put and Spd in mulberry leaves. The accumulation of Pro under NaHCO3 stress is greater than that under NaCl stress. NaCl stress also induced the up-regulation of GAD, GAD1 and GAD1 gene expression, so promoting the synthesis of GABA may be an adaptive mechanism for mulberry to cope with NaCl stress, but the expression of GAD did not change significantly and GAD gene expression lower than CK under NaHCO3 stress. Although both NaCl and NaHCO3 stress could promote the synthesis of GSH by up-regulation of GCLM expression, GSH under NaHCO3 stress was significantly higher than that under NaCl stress, the content of H2O2 was still significantly higher than that of NaCl stress, that means GSH may not play a key role in alleviating the oxidative damage in mulberry leaves caused by salt and alkali.

Physiological and proteomic responses of reactive oxygen species metabolism and antioxidant machinery in mulberry (Morus alba L.) seedling leaves to NaCl and NaHCO3 stress.

In this paper, the effects of 100 mM NaCl and NaHCO3 stress on reactive oxygen species (ROS) and physiological and proteomic aspects of ROS metabolism in mulberry seedling leaves were studied. The results showed that NaCl stress had little effect on photosynthesis and respiration of mulberry seedling leaves. Superoxide dismutase (SOD) activity and the expression of related proteins in leaves increased by varying degrees, and accumulation of superoxide anion (O2·-) not observed. Under NaHCO3 stress, photosynthesis and respiration were significantly inhibited, while the rate of O2·- production rate and H2O2 content increased. The activity of catalase (CAT) and the expression of CAT (W9RJ43) increased under NaCl stress. In response to NaHCO3 stress, the activity and expression of CAT were significantly decreased, but the ability of H2O2 scavenging of peroxidase (POD) was enhanced. The ascorbic acid-glutathione (AsA-GSH) cycle in mulberry seedling leaves was enhancement in both NaCl and NaHCO3 stress. The expression of 2-Cys peroxiredoxin BAS1 (2-Cys Prx BAS1), together with thioredoxin F (TrxF), thioredoxin O1 (TrxO1), thioredoxin-like protein CITRX (Trx CITRX), and thioredoxin-like protein CDSP32 (Trx CDSP32) were significantly increased under NaCl stress. Under NaHCO3 stress, the expression of the electron donor of ferredoxin-thioredoxin reductase (FTR), together with Trx-related proteins, such as thioredoxin M (TrxM), thioredoxin M4 (TrxM4), thioredoxin X (TrxX), TrxF, and Trx CSDP32 were significantly decreased, suggesting that the thioredoxin-peroxiredoxin (Trx-Prx) pathway's function of scavenging H2O2 of in mulberry seedling leaves was inhibited. Taken together, under NaCl stress, excessive production of O2·- mulberry seedlings leaves was inhibited, and H2O2 was effectively scavenged by CAT, AsA-GSH cycle and Trx-Prx pathway. Under NaHCO3 stress, despite the enhanced functions of POD and AsA-GSH cycle, the scavenging of O2·- by SOD was not effective, and that of H2O2 by CAT and Trx-Prx pathway were inhibited; and in turn, the oxidative damage to mulberry seedling leaves could not be reduced.

Chlorophyll synthesis and the photoprotective mechanism in leaves of mulberry (Morus alba L.) seedlings under NaCl and NaHCO3 stress revealed by TMT-based proteomics analyses.

Chlorophyll (Chl) and effective photoprotective mechanism are important prerequisites to ensure the photosynthetic function of plants under stress. In this study, the effects of 100 mmol L-1 NaCl and NaHCO3 stress on chlorophyll synthesis and photosynthetic function of mulberry seedlings were studied by physiological combined with proteomics technology. The results show that: NaCl stress had little effect on the expression of Chl synthesis related proteins, and there were no significant changes in Chl content and Chl a:b ratio. However, 13 of the 15 key proteins in the process of Chl synthesis were significantly decreased under NaHCO3 stress, and the contents of Chl a and Chl b were significantly decreased (especially Chl a). Although stomatal conductance (Gs) decreased significantly under NaCl stress, net photosynthetic rate (Pn), PSII maximum photochemical efficiency (Fv/Fm) and electron transfer rate (ETR) did not change significantly, but under NaHCO3 stress, not only Gs decreased significantly, PSII activity and photosynthetic carbon were the same. In the photoprotective mechanism under NaCl stress, NAD(P)H dehydrogenase (NDH)-dependent cyclic electron flow (CEF) enhanced, the expression of related proteins subunit, ndhH, ndhI, ndhK, and ndhM, the key enzyme of the xanthophyll cycle, violaxanthin de-epoxidase (VDE) were up-regulated, the ratio of (A + Z)/(V + A + Z) and non-photochemical quenching (NPQ) was increased. The expressions of proteins FTR and Fd-NiR were also significant up-regulated under NaCl stress, Fd-dependent ROS metabolism and nitrogen metabolism can effectively reduce the electronic pressure on Fd. Under NaHCO3 stress, the expressions of NDH-dependent CEF related proteins subunit (ndhH, ndhI, ndhK, ndhM and ndhN), VDE, ZE, FTR, Fd-NiR and Fd-GOGAT, were significant down-regulated, and ZE, CP26, ndhK, ndhM, Fd-NiR, Fd-GOGAT and FTR genes expression also significantly decreased, the photoprotective mechanism, like the xanthophyll cycle，CEF and Fd-dependent ROS metabolism and nitrogen metabolism might be damaged, resulting in the inhibition of PSII electron transfer and carbon assimilation in mulberry leaves under NaHCO3 stress.

Photochemistry and proteomics of mulberry (Morus alba L.) seedlings under NaCl and NaHCO3 stress.

In order to explore the response and adaptation mechanisms of photosynthesis of the leaves of mulberry (Morus alba L.) seedlings to saline-alkali stress. Photosynthetic activity, and the response of related proteomics of M. alba seedling leaves under NaCl and NaHCO3 stress were studied by using chlorophyll fluorescence and gas exchange technique combined with TMT proteomics. The results showed that NaCl stress had no significant effect on photosystem II (PSII) activity in M. alba seedling leaves. In addition, the expressions of proteins of the PSII oxygen-evolving complex (OEE3-1 and PPD4) and the LHCII antenna (CP24 10A, CP26, and CP29) were increased, and the photosystem I (PSI) activity in the leaves of M. alba seedlings was increased, as well as expressions of proteins, such as PsaF, PsaG, PsaH, PsaL, PsaN, and Ycf4. Under NaHCO3 stress, the activity of PSII and PSI and the expression of their protein complexes and the electron transfer-related proteins significantly decreased. NaCl stress had little effect on RuBP regeneration during dark reaction in the leaves and the expressions of glucose synthesis related proteins and net photosynthetic rate (Pn) did not decrease significantly. The leaves could adapt to NaCl stress by reducing stomatal conductance (Gs) and increasing water use efficiency (WUE). Under NaHCO3 stress, the expression of dark reaction-related proteins was mostly down-regulated, while Gs was reduced, which indicated that non-stomatal factors can be responsible for inhibition of carbon assimilation.

Species of freshwater invertebrates that are sensitive to one saline water are mostly sensitive to another saline water but an exception exists.

Coal mining and extraction of methane from coal beds generate effluent with elevated salinity or major ion concentrations. If discharged to freshwater systems, these effluents may have adverse environmental effects. There is a growing body of work on freshwater invertebrates that indicates variation in the proportion of major ions can be more important than salinity when determining toxicity. However, it is not known if saline toxicity in a subset of species is representative of toxicity across all freshwater invertebrates. If patterns derived from a subset of species are representative of all freshwater invertebrates, then we would expect a correlation in the relative sensitivity of these species to multiple saline waters. Here, we determine if there is a correlation between the acute (96 h) lethal toxicity in freshwater invertebrates to synthetic marine salts (SMS) and sodium bicarbonate (NaHCO3) added to dechlorinated Sydney tap water. NaHCO3 is a major component of many coal bed effluents. However, most salinization in Australia exhibits ionic composition similar to seawater, which has very little HCO3- Across all eight species tested, NaHCO3 was 2-50 times more toxic than SMS. We also observed strong correlations in the acute toxicity of seven of the tested species to SMS and NaHCO3 The strongest relationship (LC50 r2 = 0.906) was dependent on the exclusion of one species, Paratya australiensis (Decopoda: Atyidae), which was the most sensitive species tested to NaHCO3, but the second-most tolerant of SMS. We conclude that differences in the toxicity of different proportions of major ions can be similar across a wide range of species. Therefore, a small subset of the invertebrate community can be representative of the whole. However, there are some species, which based on the species tested in the current study appear to be a minority, that respond differently to saline effluent and need to be considered separately. We discuss the implications of this study for the management of saline coal bed waters.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

An evaluation of the residual toxicity and chemistry of a sodium hydroxide-based ballast water treatment system for freshwater ships.

Nonnative organisms in the ballast water of freshwater ships must be killed to prevent the spread of invasive species. The ideal ballast water treatment system (BWTS) would kill 100% of ballast water organisms with minimal residual toxicity to organisms in receiving waters. In the present study, the residual toxicity and chemistry of a BWTS was evaluated. Sodium hydroxide was added to elevate pH to >11.5 to kill ballast water organisms, then reduced to pH <9 by sparging with wet-scrubbed diesel exhaust (the source of CO2 ). Cladocerans (Ceriodaphnia dubia), amphipods (Hyalella azteca), and fathead minnows (Pimephales promelas) were exposed for 2 d to BWTS water under an air atmosphere (pH drifted to ≥9) or a 2.5% CO2 atmosphere (pH 7.5-8.2), then transferred to control water for 5 d to assess potential delayed toxicity. Chemical concentrations in the BWTS water met vessel discharge guidelines with the exception of concentrations of copper. There was little to no residual toxicity to cladocerans or fish, but the BWTS water was toxic to amphipods. Maintaining a neutral pH and diluting BWTS water by 50% eliminated toxicity to the amphipods. The toxicity of BWTS water would likely be minimal because of rapid dilution in the receiving water, with subsurface release likely preventing pH rise. This BWTS has the potential to become a viable method for treating ballast water released into freshwater systems.

In situ and laboratory toxicity of coalbed natural gas produced waters with elevated sodium bicarbonate.

Some tributaries in the Powder River Structural Basin, USA, were historically ephemeral, but now contain water year round as a result of discharge of coalbed natural gas (CBNG)-produced waters. This presented the opportunity to study field sites with 100% effluent water with elevated concentrations of sodium bicarbonate. In situ experiments, static renewal experiments performed simultaneously with in situ experiments, and static renewal experiments performed with site water in the laboratory demonstrated that CBNG-produced water reduces survival of fathead minnow (Pimephales promelas) and pallid sturgeon (Scaphirhynchus albus). Age affected survival of fathead minnow, where fish 2 d posthatch (dph) were more sensitive than 6 dph fish, but pallid sturgeon survival was adversely affected at both 4 and 6 dph. This may have implications for acute assays that allow for the use of fish up to 14 dph. The survival of early lifestage fish is reduced significantly in the field when concentrations of NaHCO(3) rise to more than 1500 mg/L (also expressed as >1245 mg HCO(3) (-) /L). Treatment with the Higgin's Loop technology and dilution of untreated water increased survival in the laboratory. The mixing zones of the 3 outfalls studied ranged from approximately 800 m to 1200 m below the confluence. These experiments addressed the acute toxicity of effluent waters but did not address issues related to the volumes of water that may be added to the watershed.

Bicarbonate toxicity to Ceriodaphnia dubia and the freshwater shrimp Paratya australiensis and its influence on zinc toxicity.

Bicarbonate is often a major ionic constituent associated with produced waters from methane gas extraction and coal mining, yet few studies have determined its specific toxicity. Currently, the environmental risk of bicarbonate anion in water discharges is assessed based on the toxicity of sodium chloride or artificial seawater and is regulated via electrical conductivity. Increased NaHCO(3) added to Ceriodaphnia dubia in synthetic or natural water gave similar 48-h 10% effective concentration (EC10) values of 1750 ± 125 mg NaHCO(3)/L (mean ± standard error) and 1670 ± 180 mg NaHCO(3)/L, respectively. Bicarbonate was toxic to C. dubia in both waters with conductivities above 1900 µS/cm. In contrast, when conductivity was elevated with NaCl, toxicity to C. dubia was observed only above 2800 µS/cm. Bicarbonate also impaired C. dubia reproduction with an EC10 of 340 mg NaHCO(3)/L. Major ion composition also influenced Zn bioavailability, a common co-occurring metal contaminant in coal mine waters, with sublethal concentrations of NaHCO(3) and elevated pH increasing Zn toxicity. Higher pH was the dominant parameter determining a 10-fold increase in the 48-h 50% effective concentration (EC50) for Zn toxicity to C. dubia at pH 8.6 of 34 µg Zn/L (95% confidence limit = 32-37 µg Zn/L) compared with the Zn toxicity at approximately circumneutral pH. Exposure of the freshwater shrimp Paratya australiensis (Atyidae) in natural water to increasing bicarbonate gave a mean 10-d 10% lethal concentration (LC10) of 850 ± 115 mg NaHCO(3)/L, associated with a mean conductivity EC10 of 1145 µS/cm, which is considerably lower than toxicity of NaCl and artificial seawater to this species reported elsewhere. Because toxicity was influenced by salt composition, specific ions should be regulated rather than conductivity alone in mine wastewater discharges.

Acute toxicity of sodium bicarbonate, a major component of coal bed natural gas produced waters, to 13 aquatic species as defined in the laboratory.

Water produced during coal bed natural gas (CBNG) extraction in the Powder River Structural Basin of Wyoming and Montana (USA) may contain concentrations of sodium bicarbonate (NaHCO3) of more than 3000 mg/L. The authors evaluated the acute toxicity of NaHCO3, also expressed as bicarbonate (HCO3(-)), to 13 aquatic organisms. Of the 13 species tested, 7 had a median lethal concentration (LC50) less than 2000 mg/L NaHCO3, or 1300 mg/L HCO3(-). The most sensitive species were Ceriodaphnia dubia, freshwater mussels (Lampsilis siliquoidea), pallid sturgeon (Scaphirhynchus albus), and shovelnose sturgeon (Scaphirhynchus platorynchus). The respective LC50s were 989 mg/L, 1120 mg/L, 1249 mg/L, and 1430 mg/L NaHCO3, or 699 mg/L, 844 mg/L, 831 mg/L, and 1038 mg/L HCO3(-). Age affected the sensitivity of fathead minnows, even within life stage. Two days posthatch, fathead minnows were more sensitive to NaHCO3 and HCO3(-) compared with 4-d-old fish, even though fish up to 14 d old are commonly used for toxicity evaluations. The authors recommend that ion toxicity exposures be conducted with organisms less than 24 h posthatch to ensure that experiments document the most sensitive stage of development. The results of the present study, along with historical and current research regarding the toxicity of bicarbonate, may be useful to establish regulatory standards for HCO3(-). This article is a US Government work and is in the public domain in the USA.

The chronic toxicity of sodium bicarbonate, a major component of coal bed natural gas produced waters.

Sodium bicarbonate (NaHCO3) is the principal salt in coal bed natural gas produced water from the Powder River Structural Basin, Wyoming, USA, and concentrations of up to 3000 mg NaHCO3/L have been documented at some locations. No adequate studies have been performed to assess the chronic effects of NaHCO3 exposure. The present study was initiated to investigate the chronic toxicity and define sublethal effects at the individual organism level to explain the mechanisms of NaHCO3 toxicity. Three chronic experiments were completed with fathead minnows (Pimephales promelas), 1 with white suckers (Catostomus commersoni), 1 with Ceriodaphnia dubia, and 1 with a freshwater mussel, (Lampsilis siliquoidea). The data demonstrated that approximately 500 mg NaHCO3/L to 1000 mg NaHCO3/L affected all species of experimental aquatic animals in chronic exposure conditions. Freshwater mussels were the least sensitive to NaHCO3 exposure, with a 10-d inhibition concentration that affects 20% of the sample population (IC20) of 952 mg NaHCO3/L. The IC20 for C. dubia was the smallest, at 359 mg NaHCO3/L. A significant decrease in sodium-potassium adenosine triphosphatase (Na(+)/K(+) ATPase) together with the lack of growth effects suggests that Na(+)/K(+) ATPase activity was shut down before the onset of death. Several histological anomalies, including increased incidence of necrotic cells, suggested that fish were adversely affected as a result of exposure to >450 mg NaHCO3/L. This article is a US Government work and is in the public domain in the USA.

The effect of bicarbonate on menadione-induced redox cycling and cytotoxicity: potential involvement of the carbonate radical.

We have investigated the effect of NaHCO3 on menadione redox cycling and cytotoxicity. A cell-free system utilized menadione and ascorbic acid to catalyze a redox cycle, and we utilized murine hepatoma (Hepa 1c1c7) cells for in vitro experiments. Experiments were performed using low (2 mmol/L) and physiological (25 mmol/L) levels of NaHCO3 in buffer equilibrated to physiological pH. Using oximetry, ascorbic acid oxidation, and ascorbyl radical detection, we found that menadione redox cycling was enhanced by NaHCO3. Furthermore, Hepa 1c1c7 cells treated with menadione demonstrated cytotoxicity that was significantly increased with physiological concentrations of NaHCO3 in the media, compared with low levels of NaHCO3. Interestingly, the inhibition of superoxide dismutase (SOD) with 2 different metal chelators was associated with a protective effect against menadione cytotoxicity. Using isolated protein, we found a significant increase in protein carbonyls with menadione-ascorbate-SOD with physiological NaHCO3 levels; low NaHCO3 or SOD-free reactions produced lower levels of protein carbonyls. In conclusion, these findings suggest that the hydrogen peroxide generated by menadione redox cycling together with NaHCO3-CO2 are potential substrates for SOD peroxidase activity that can lead to carbonate-radical-enhanced cytotoxicity. These findings demonstrate the importance of NaHCO3 in menadione redox cycling and cytotoxicity.

[Protective effects of La (NO3)3 on ryegrass seedlings photosynthetic apparatus under NaHCO3 stress].

This paper studied the effects of foliar spraying different concentration La(NO3)3 on the photosynthesis, chlorophyll fluorescence parameters, Mehler reaction, and xanthophyll cycle of ryegrass seedlings under the stress of 150 mmol NaHCO3 x L(-1). Foliar spraying low concentration (0.05 mmol x L(-1)) La (NO3)3 could significantly decrease the decrement of net photosynthesis rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), and stomatal limited value (Ls) and the increment of intercellular CO2 concentration (Ci) under NaHCO3 stress, efficiently alleviate the inhibitory effects of NaHCO3 stress on PS II photochemical quenching (q(p)), actual photochemical efficiency (phi(PS II)), photosynthetic carbon assimilation- dependent electron transport rate (ETRp), and Mehler reaction- dependent electron transport rate (ETRm), enhance the activities of superoxide dismutase, peroxidase, and ascorbate peroxidase, the non-photochemical energy dissipation (NPQ), the xanthophyll cycle pool (V+A+Z), and the de-epoxidation extent of xanthophyll cycle (A+Z)/(V+A+Z), and thereby, alleviate the damage of photosynthetic apparatus caused by NaHCO3 stress. However, treating with high concentration (0.5 mmol x L(-1)) La(NO3)3 had no obvious alleviation effects. It was suggested that foliar spraying an appropriate concentration La (NO3)3 could not only alleviate the decrease of ryegrass seedling' s photosynthetic rate induced by nonstomata factors and the inhibition of photochemical efficiency, but also accelerate the Mehler reaction under NaHCO3 stress. With the accelerated Mehler reaction, excessive excitation energy could directly be consumed, and the xanthophyll cycle-dependent thermal dissipation could be promoted to efficiently protect the photosynthetic apparatus against photo-damage under NaHCO3 stress. Also, the active oxygen produced by the accelerated Mehler reaction could be scavenged by the enhanced anti-oxidative enzyme activities.

Biological properties of a neutralized 2.5% sodium hypochlorite solution.

OBJECTIVES: The objective of this study was to evaluate the influence of neutralizing a 2.5% NaOCl solution on its cytotoxicity, genotoxicity, and tissue-dissolving potential. STUDY DESIGN: The cytotoxicity and the genotoxicity of Dakin, a 2.5% NaOCl solution, and a neutralized 2.5% NaOCl solution were assessed according to ISO 10993 standards. The weight of palatal mucosa samples placed in neutralized 2.5% NaOCl, 2.5% NaOCl was recorded over time as well as the pH of the solutions. RESULTS: The neutralized 2.5% NaOCl solution was 10-fold more cytotoxic than the 2.5% NaOCl solution. None of the solutions was genotoxic. The 2.5% NaOCl solution had a better tissue-dissolving capacity than the neutralized 2.5% NaOCl solution. The pH of the 2.5% NaOCl solution and neutralized 2.5% NaOCl solution decreased from 12 to 9 and from 7.5 to 5.6, respectively. CONCLUSION: Neutralizing a 2.5% NaOCl solution increased its cytotoxicity, did not induce any genotoxic effect, and reduced its tissue-dissolving ability.

Gout induced by intoxication of sodium bicarbonate in Korean native broilers.

Gout is a metabolic disorder that results in hyperuricemia and the deposition of positively birefringent monosodium urate crystals in various parts of the body. Intoxication of sodium bicarbonate (SBC) for 35 days in Korean native broilers was investigated. Sixty birds, aged 2 weeks, divided into 5 groups were exposed to excess SBC: 2 g/L (group A), 7.5 g/L (group B), 20 g/L (group C), 40 g/L (group D). Toxicopathological examination of all exposed birds revealed the manifestation of visceral and articular gout in group C, while birds of group D showed acute kidney damage with manifestation of excessive visceral gout. Interestingly, few birds in group D also showed signs of rare condition of acute articular gout. Dose-dependent increments in erythrocytic count, hematocrit values, and hemoglobin levels of the exposed birds were observed. Hypernatremia, hyperuricemia, hypokalemia, and hypochloremia were common findings among exposed birds. Microscopic examination of birds that manifested visceral gout revealed significant urate deposit, tubular necrosis, and tophi formation in renal interstitium. These findings provide a pathophysiological link that SBC intoxication may support hyperuricemia, which is an independent risk factor for gout and other renal dysfunctions. Further study is required to delineate the effect of lowering uric acid on progression of gout and other renal diseases.

Lack of promotion of urinary bladder carcinogenesis by sodium bicarbonate and/or L-ascorbic acid in male ODS/Shi-od/od rats synthesizing alpha 2 mu-globulin but not L-ascorbic acid.

The study was designed to investigate whether sodium bicarbonate (NaHCO3) and/or L-ascorbic acid (AsA) promote urinary bladder carcinogenesis in male ODS/Shi-od/od (ODS) rats, which, unlike male F344 rats, are resistant to sodium L-ascorbate (Na-AsA)-promoting effects. Whereas F344 rats can synthesize AsA and alpha 2 mu-globulin (A2 mu-G), only A2 mu-G in produced in ODS rats. The two strains were given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) in their drinking water for 2 wk and then were fed basal CA-1 diet supplemented with 3% NaHCO3 plus 5% AsA (NaHCO3 + AsA), 3% NaHCO3, 5% AsA, or no chemicals for 32 wk. ODS rats given BBN-NaHCO3 or BBN-(NaHCO3 + AsA) had only a few small carcinomas in the urinary bladder, like those receiving BBN alone or BBN-AsA. In contrast, F344 rats administered BBN-NaHCO3 or BBN-(NaHCO3 + AsA) had many more, larger, carcinoma than animals of the same strain given BBN alone or BBN-AsA. AsA alone did not have any effect in either strain. Administration of NaHCO3 alone or NaHCO3 + AsA was associated with significant elevation of urinary pH and Na+ concentration to the same extent in both strains but, again, AsA alone was without effect. NaHCO3 + AsA and AsA alone increased the urinary concentration of total ascorbic acid in both strains but the observed levels wer lower in ODS rats. The results indicate that ODS rats are resistant to the modifying effects of NaHCO3 and/or AsA on two-stage urinary bladder carcinogenesis, and thus that the susceptibility to the promotional activity of sodium-salt-type compounds may be regulated by factors other than A2 mu-G-synthesizing ability and urinary levels of pH, Na+ and total ascorbic acid.

Dose-dependent amplification by L-ascorbic acid of NaHCO3 promotion of rat urinary bladder carcinogenesis.

The dose dependence of L-ascorbic acid (AsA) copromotion of urinary bladder carcinogenesis with continuous concomitant administration of NaHCO3 was investigated. In the first experiment, 83 male F344 rats were all given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 4 wk and then divided into 5 groups, which received basal diet (Oriental MF) containing AsA at 0, 1, 2, 3.5, or 5% plus 1.5% NaHCO3 for 32 wk. Relative urinary bladder weights in the 5% AsA group were significantly increased as compared to the 0 or 1% group values due to the development of tumors. Both the incidence and number of microscopic urinary bladder lesions (tumors and preneoplastic lesions) showed dose-dependent increases. Furthermore, the sizes of the urinary bladder tumors (carcinomas and papillomas) were significantly increased with the highest dose, 5-bromo-2'-deoxyuridine labeling indices showed slightly increased proliferation in preneoplastic lesions of the urinary bladder epithelium with 5% AsA treatment. In a separate experiment, scanning electron microscopic observation revealed that administration of 5% AsA plus 1.5% NaHCO3 for 8 wk, without BBN, altered the urinary bladder surface. Elevation of urinary bladder epithelium AsA content, as well as urinary AsA, was also noted. Ornithine decarboxylase (ODC) activity and ODC messenger RNA levels in urinary bladder epithelium of rats treated with 1.5% NaHCO3 plus 5% AsA for 8 wk showed no statistically significant differences as compared to the control group. The results indicate that AsA amplifies the rat urinary bladder carcinogenesis promotion activity of NaHCO3 and that its intensity of action depends on the dose, particularly at high dose.

Inhibiting effects of diethylmaleate or NH4Cl on NaHCO3, but not butylated hydroxyanisole, promotion of urinary bladder carcinogenesis in male F344 rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine.

The modifying potential of diethylmaleate (DEM) and NH4Cl on promotion by butylated hydroxyanisole (BHA) or NaHCO3 of urinary bladder carcinogenesis in rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was investigated. Six week old animals received 0.05% BBN for 4 weeks and then BHA (2%) + DEM (0.15%), BHA + NH4Cl (1%), NaHCO3 (3%) + DEM, NaHCO3 + NH4Cl, BHA, DEM, NH4Cl or no supplement, administered during experimental weeks 5-36. BHA and NaHCO3 clearly amplify the induction of papillary or nodular (PN) hyperplasias and papillomas in rats initiated with BBN. The promoting activity of BHA was not affected by simultaneous administration of DEM or NH4Cl. The enhancing effects of NaHCO3, in contrast, were clearly diminished by concurrent administration of either of these agents. DEM itself did not influence lesion development whereas NH4Cl reduced the incidence of papillomas. In a second experiment, rats exposed to the same protocol were killed at week 8, and assessed for levels of lipid peroxides in the bladder tissue. No remarkable alterations were observed in any group. Thus, the fact that DEM did exert inhibiting effects on tumor promotion by NaHCO3 without decreasing the urinary sodium ion concentration or pH and influence on lipidperoxide levels, suggests essential differences in the mechanisms of action of different types of bladder promoters.

Roles of bladder distension, urinary pH and urinary sodium ion concentration in cell proliferation of urinary bladder epithelium in rats ingesting sodium salts.

The relative importance of bladder distension, urinary pH and sodium ion concentration for cell proliferation in the bladder epithelium of rats fed various sodium salts was investigated. When a diet containing 5% NaHCO3 was fed to male rats, the bladder epithelium showed an increase in replicating cells, together with distension, increased urine pH and high urine sodium ion concentration. Cell proliferation also occurred when bladders were subjected to distension in vivo by mechanical (female) or physiological (male) means. Inclusion of CaCO3 in the diet produced high urinary pH without alteration in the other factors and did not induce cell proliferation. Increased proliferation occurred when CaCO3 was combined with these mechanical or physiological treatments. Thus, high urinary pH was of secondary importance to bladder distension as a causative factor, but acted to enhance cell proliferation when distension occurred. Similar findings were obtained with regard to sodium ion concentration. In conclusion, this study demonstrated that bladder distension is one of the prerequisites for promoter-induced cell proliferation in the bladder epithelium, with high urinary pH and sodium ion concentration.