A review of some physiological and toxicological responses of freshwater fish to acid stress

Synopsis Data relating to the specific effect of low pH on growth of freshwater fishes are ambiguous. Reproductive failure resulting from acid stress appears to be related to an upset in calcium metabolism and to faulty deposition of protein in developing oocytes. It appears that the ’no effect‘ level of pH depression for successful reproduction is around 6.5. Data on behaviorial responses of freshwater fish to acid stress and CO₂ are described. Most fish appear to be indifferent to pH within the range of approximately 10.5 to 5.5 and between 7.4 and 4.5 CO₂ appears to be the main directive factor. In cases of severe acid stress alteration of gill membranes and/or coagulation of gill mucus occurs and death due to hypoxia may result from a lengthening of the water-blood diffusion distance. Several reports agree that acid stress causes an upset of electrolyte homeostasis in fish but effects of low pH on osmotic permeability are largely lacking. Most hatcheryreared salmonids can tolerate pH 5.0 indefinitely but below this level the homeostatic electrolyte and osmotic regulatory mechanisms become inadequate. When fish are subjected to debilitating acid stress blood pH decreases possibly as the result of flux of H⁺ ions across gill membranes into the blood. This could change transepithelial potential and allow a blood, to-water diffusion of Na⁺ ions down an electrochemical gradient. Lowered ambient pH may interfere with gill calcium levels increasing permeability to both H⁺ and Na⁺ ions or an acidemia may occur as the result of a decrease in the excretion of metabolically produced H⁺ ions and CO₂. When the capacity of the buffer mechanisms is exceeded the blood pH drops and the capacity of hemoglobin to transport oxygen is decreased.     

Enzyme activities in concentrated solutions of glycinebetaine and other solutes

The activities of a number of enzymes in concentrated solutions of glycinebetaine and other solutes have been studied. Glycinebetaine, in contrast to electrolytes such as NaCl, was found to be noninhibitory up to 500 mM. This is compatible with the postulated role of glycinebetaine in cytoplasmic osmoregulation. Partial protection against NaCl inhibition was afforded by glycinebetaine in some cases. More detailed studies on glycinebetaine —NaCl-enzyme interactions were carried out using malate dehydrogenase (decarboxylating) from Hordeum vulgare.Abbreviations TES N-tris[hydroxymethyl]methyl-2-aminoethane sulphonic acid - MES 2[N-Morpholino]ethane sulphonic acid     

Spherical Boundary Conditions: A Finite and System Size Independent Geometry for Simulations of Electrolytic Liquids

The system size dependence of the thermodynamic properties of electrolytic systems in "Spherical Boundary Conditions" (SBC) have been examined in this work. Coulombic systems were simulated with different system sizes (N ) for a wide range of concentrations, different ionic charges and solvent permittivities. The effects of system size upon the mean internal energy ?U? and mean ionic activity coefficient ?γ _±? values were determined. Our results indicated that there was no dependence of the thermodynamic properties upon system size in the non-Euclidean geometry. Different methods of extrapolating the thermodynamic properties to infinite numbers were studied in detail. In contrast to the Euclidean geometry, the method of extrapolating ?U? or ?γ _±? versus N ^-1, N ^-2/3 and N ^-1/3 was not statistically justifiable nor advantageous. Therefore, SBC is well suited to simulating systems involving long-range electrostatic interactions because the results do not dependent upon system size.     

Survival of Rats Undergoing Continuous Bile Drainage Depends on Maintenance of Circadian Rhythm of Bile Secretion

It is very difficult to collect bile secretions from animals for extended periods of time. We compared the use of saline or water as drinking fluids to sustain the animals, which were being continuously drained of bile. Complete bile drainage was performed in 16 male Wistar rats by surgical intervention. After surgery, 8 rats were given tap water, and the other 8 were given normal saline for water. The rats that received water rapidly lost weight after bile drainage, and all died within 8 days after the operation. In contrast, all rats that drank saline maintained their body weight and survived 14 days or longer after surgery. Serum biochemistry of the rats with water intake on the third day after bile drainage revealed hyponatremia, hypochloremia, and acute renal failure resulting in hyperkalemia. In contrast, electrolyte balance and renal function were normal in the rats with saline intake, and bile was secreted continuously with a circadian rhythm. These results clearly demonstrate that saline as drinking water is essential to the replacement of lost fluids and loss of electrolytes due to bile drainage. Further, saline proved efficacious for sustaining experimental animals undergoing continuous bile collection.     

草鱼血液学的研究：Ⅱ.血清电解质和尿素氮的周年变化

本文研究了草鱼稚鱼血清钾、钠、钙、氯、无机磷和尿素氮含量的周年变动规律,分析了水温、体重对上述血液化学成分的影响。结果显示其周年变动无一定规律性可循。血清钠、氯变动辐度较小,无机磷和尿素氮变动幅度较大,幅值约有4倍。水温与血清钾显示正相关(P≤0.05),与钠、钙显示负相关(P≤0.01,P≤0.05)。血清钠、尿素氮有随体重增加含量增高的趋势,而钾却显著减少。     

Effect of bacoside A on membrane-bound ATPases in the brain of rats exposed to cigarette smoke

Membrane-bound enzymes play a vital role in neuronal function through maintenance of membrane potential and impulse propagation. We have evaluated the harmful effects of chronic cigarette smoking on membrane-bound ATPases and the protective effect of Bacoside A in rat brain. Adult male albino rats were exposed to cigarette smoke for a period of 12 weeks and simultaneously administered with Bacoside A (the active principle isolated from Bacopa monniera) at a dosage of 10 mg/kg b.w/day, p.o. The levels of lipid peroxides as marker for evaluating the extent of membrane damage, the activities of Na+/K+-ATPase, Ca2+-ATPase and Mg2+-ATPase, and associated cations sodium (Na+), potassium (K+), calcium (Ca2+), and magnesium (Mg2+) were investigated in the brain. Neuronal membrane damage was evident from the elevated levels of lipid peroxides and decreased activities of membrane-bound enzymes. Disturbances in the electrolyte balance with accumulation of Na+ and Ca2+ and depletion of K+ and Mg2+ were also observed. Administration of Bacoside A inhibited lipid peroxidation, improved the activities of ATPases, and maintained the ionic equilibrium. The results of our study indicate that Bacoside A protects the brain from cigarette smoking induced membrane damage.     

花色豚鼠与白化豚鼠静脉血电解质、酸碱平衡及血气的比较学研究

目的比较研究花色豚鼠与白化豚鼠静脉血电解质、酸碱平衡及血气情况。方法分别取健康成年花色豚鼠和白化豚鼠,利用便携式多功能麻醉机经异氟烷吸入麻醉后,腹主静脉取血,经NOVA血气．电解质分析仪全自动分析测定电解质、酸碱平衡及血气等指标。结果花色豚鼠的Cl-、pH、SBC、PO2、SV O2、O2ct均显著低于白化豚鼠（P〈0．05,P〈0．01）,而PCO2显著高于白化豚鼠（P〈O．05）。结论花色豚鼠的携氧能力明显低于白化豚鼠,可以作为血瘀证和亚健康模型研究较好的实验动物。     

Plasma hormonal and electrolyte alterations in cycling buffaloes (Bubalus bubalis) during hot summer months

Plasma levels of progesterone, prolactin, luteinizing hormone, and electrolytes were monitored by radioimmunoassay in ten cycling buffaloes maintained at Punjab Agricultural University, Ludhiana during the hot summer months of June–July. The plasma progesterone concentration ranged from 0.28±0.04 to 3.09±0.03 ng/ml at various stages of the oestrous cycle. Prolactin values ranged from 319±23 to 371±25 ng/ml and LH levels from 0.95±0.05 to 1.35±0.08 ng/ml. Concentrations differed significantly (P0.05) at various stages of the cycle. Levels of electrolytes, viz. Ca^{+ +}, Na⁺ and K⁺, were well within the normal range. The high levels of prolactin, progesterone and LH during the hot summer were assessed in relation to poor reproductive efficiency in buffaloes.     

再水合溶液能有效改善急性脱水女举重运动员的运动表现

本研究旨在探讨女子举重运动员急性脱水后口服4种不同组成的溶液,对液体存留率、胃肠道舒适度、血液值和无氧动力的影响。本研究以12位大学生女子举重运动员为对象,采交叉、平衡次序设计;研究参与者于脱水2%体重后分别补充相当于1.5倍脱水量的低渗透压电解质液(HES)、等渗透压电解质液(IES)、运动饮料(SB)或纯水(W),补充时间为脱水后立即、再水合期的30 min、60 min及90 min。再水合期间记录胃肠舒适分数、测量体重(计算液体存留率),并采集静脉血以测量血液渗透压、葡萄糖及钠、钾与氯离子,于脱水前与再水合期120 min时进行Wingate无氧动力测验。研究结果显示:补充HES、IES及运动饮料(SB)于再水合期90 min时的胃肠道舒适分数显著低于补充纯水(W)、而补充3种溶液于再水合期60 min时的血糖值则显著高于补充纯水(W),补充HES于再水合期120 min时的血钾值显著高于补充运动饮料(SB)及纯水(W);但补充4种溶液后的无氧动力与液体存留率并无显著差异。本研究证实举重运动员急性脱水后补充4种不同口服再水合溶液并不会影响再水合后的无氧动力,但补充含有糖类及电解质的溶液能有较佳的胃肠道舒适度,并血糖与血液电解质有维持的效果。     

Urinary markers of nephrotoxicity following administration of 2 bromoethanamine hydrobromide a comparison with hexachlorobutadiene

2 bromoethanamine hydrobromide (BEA) has been widely considered to be a target selective nephrotoxin that causes necrosis of the medulla in 24-48 h, but recent reports suggest that early cortical injury is also associated with this lesion. In order to assess the cortical effects of BEA (100 mg kg^-1 bw single ip injection), several urinary markers of renal injury were evaluated over a 7 day period in male Wistar Albino rats. Hexachlorobutadiene (HCBD 150 mg kg^-1 bw in peanut oil ip), a renal toxin which targets selectively for the proximal tubule, was used as a comparison. After BEA treatment, urinary levels of alanine aminopeptidase, gamma-glutamyl-transpeptidase, alkaline phosphatase and glucose increased transiently. Each of the proximal tubule marker enzymes peaked earlier following HCBD treatment and elevation of alanine aminopeptidase and gamma glutamyl transpeptidase was sustained for longer periods than for BEA. Following BEA treatment, lactate dehydrogenase rose prominently on day 1 followed by a return to control values on day 2 and a further rise on day 3 and remained high until the end of the study. BEA also increased the urinary excretion of total protein and albumin. After HCBD treatment, lactate dehydrogenase showed a transient elevation and glucose levels were slightly increased. Based on the present observations the changes induced by BEA administration on urinary markers of renal injury are different from those observed following HCBD treatment. These findings suggest that BEA toxicity also involves other parts of the kidney besides the papilla.