Pyridoxal isonicotinoyl hydrazone and analogues

Summary The ultraviolet-visible absorption spectra of the orally effective iron chelator, pyridoxal isonicotinoyl hydrazone (PIH), and three analogues, pyridoxal benzoyl hydrazone (PBH), pyridoxalp-methoxybenzoyl hydrazone (PpMBH) and pyridoxalm-fluorobenzoyl hydrazone (PmFBH) have been measured in aqueous solution with various concentrations of added acid or alkali. Assignment of absorption bands to various molecular species in equilibrium in aqueous solution is made by reference to their acid ionisation constants. All four hydrazones were stable at physiologial pH, but hydrolysed in strongly acidic and basic solutions, resulting in the liberation of pyridoxal and the acid hydrazide. In acidic solutions this resulted in a dramatic decrease in the intensity of absorption at wavelengths of 225 nm and above 300 nm, allowing a quantitative estimate of the degree of acid-catalysed hydrolysis of the ligands. These results indicate that for oral administration the chelator should be administered with calcium carbonate or provided with an enteric coating to minimise acid-catalysed hydrolysis in the stomach. At high pH, base-catalysed hydrolysis occurred, resulting in a decrease in the absorption at a wavelength of 387 run.     

Iron chelators of the pyridoxal isonicotinoyl hydrazone class Part I. Ionisation characteristics of the ligands and their relevance to biological properties

The orally effective iron chelator, pyridoxal isonicotinoyl hydrazone (PIH), and five analogues, pyridoxal benzoyl hydrazone (PBH), pyridoxal p-methoxybenzoyl hydrazone ((PpMBH), pyridoxal m-fluorobenzoyl hydrazone (PmFBH), 3-hydroxy- isonicotinaldehyde isonicotinoyl hydrazone (IIH) and salicylaldehyde isonicotinoyl hydrazone (SIH) were synthesised and characterised and their acid dissociation constants measured by glass electrode potentiometry and UV—Vis spectrophotometry. Analysis of the data showed that at physiological pH all of the ligands are predominantly (av. 80%) in the form of the neutral molecule, allowing passage through cell membranes and access to intracellular iron pools. The results are discussed in the context of the development of an orally effective iron chelator for clinical use.     

Metallo-β-lactamase and phosphotriesterase activities of some zinc(II) complexes

Metallo-β-lactamases (mβl) and phosphotriesterase (PTE) are zinc(II) enzymes, which hydrolyze the β-lactam antibiotics and toxic organophosphotriesters, respectively. In the present work, we have synthesized a few asymmetric phenolate-based ligands by sequential Mannich reaction and their corresponding zinc(II) complexes. These zinc(II) complexes were studied for their mβl and PTE activities. It is shown that the zinc(II) complexes can hydrolyze oxacillin, the β-lactam antibiotic, at much higher rates as compared to the hydrolysis of p-nitrophenyl diphenylphosphate (PNPDPP), the phosphotriester. Among the complexes studied, the binuclear asymmetric complex 1 having a water molecule coordinated to one of the zinc(II) ions exhibits much better mβl activity than the mononuclear complexes. However, the mononuclear zinc(II) complexes having labile chloride ions exhibit significant PTE activity, which can be ascribed to the replacement of chloride ions by hydroxide ions during hydrolysis reactions.     

EDTA chelation effects on urinary losses of cadmium, calcium, chromium, cobalt, copper, lead, magnesium, and zinc

The efficacy of a chelating agent in binding a given metal in a biological system depends on the binding constants of the chelator for the particular metals in the system, the concentration of the metals, and the presence and concentrations of other ligands competing for the metals in question. In this study, we make a comparison of the in vitro binding constants for the chelator, ethylenediaminetetraacetic acid, with the quantitative urinary excretion of the metals measured before and after EDTA infusion in 16 patients. There were significant increases in lead, zinc, cadmium, and calcium, and these increases roughly corresponded to the expected relative increases predicted by the EDTA-metal-binding constants as measured in vitro. There were no significant increases in urinary cobalt, chromium, or copper as a result of EDTA infusion. The actual increase in cobalt could be entirely attributed to the cobalt content of the cyanocobalamin that was added to the infusion. Although copper did increase in the post-EDTA specimens, the increase was not statistically significant. In the case of magnesium, there was a net retention of approximately 85% following chelation. These data demonstrate that EDTA chelation therapy results in significantly increased urinary losses of lead, zinc, cadmium, and calcium following EDTA chelation therapy. There were no significant changes in cobalt, chromium, or copper and a retention of magnesium. These effects are likely to have significant effects on nutrient concentrations and interactions and partially explain the clinical improvements seen in patients undergoing EDTA chelation therapy.     

Observations on the use of a cation exchange resin for the preparation of metal-depleted media for lymphocyte culture

A chelating resin specific for divalent cations (Chelex) was used to prepare metal-depleted media for lymphocyte culture. A batch procedure (resin in pH 7.4 phosphate buffer/specimen, 1:1) removed 70-80% of iron, 77-87% of copper and 88-98% of zinc, calcium and magnesium. At variance with other reports, when a resin/specimen ratio of 1:4 was used, iron chelation decreased to 40%, whereas other cation chelation remained unchanged. Best chelation for iron and calcium was obtained at pH 5-6.4; for copper, zinc and magnesium, at pH 7.4-8.0. During the procedure protein content decreased by 8-10%; arginine and lysine by 80%; asparagine, cystine, tyrosine and phenylalanine by 60%, other amino acids by 35%. These new data suggest that cation-depleted media prepared with Chelex may be used to study the effects of cations on lymphocytes in culture, provided that the most appropriate pH and resin/specimen ratio are selected and adequate amino acid replacement is performed. Results on normal human lymphocytes are reported.     

PCTH: a novel orally active chelator of the aroylhydrazone class that induces iron excretion from mice

beta-Thalassaemia major is an inherited blood disorder which is complicated by repeated blood transfusion and excessive gastrointestinal iron (Fe) absorption, which leads to toxic Fe overload. Current treatment using the chelator, desferrioxamine (DFO), is expensive and cumbersome since the drug requires long subcutaneous infusions and it is not orally active. A novel chelator, 2-pyridylcarboxaldehyde 2-thiophenecarboxyl hydrazone (PCTH), was recently designed and shown to have high Fe chelation efficacy in vitro. The aim of this investigation was to examine the Fe chelation efficacy of PCTH in vitro implementing primary cultures of cardiomyocytes and in vivo using mice. We showed that PCTH was significantly (P<0.005) more effective than DFO at mobilising (59)Fe from prelabelled cardiomyocytes. Moreover, PCTH prevented the incorporation of (59)Fe into ferritin during Fe uptake from (59)Fe-labelled transferrin. These effects were important to assess as cardiac complications caused by Fe deposition are a major cause of death in beta-thalassaemia major patients. Further studies showed that PCTH was orally active and well tolerated by mice at doses ranging from 50 to 200 mg/kg, twice daily (bd), for 2 days. A dose-dependent increase in faecal (59)Fe excretion was observed in the PCTH-treated group. This level of Fe excretion at 200 mg/kg was similar to the same dose of the orally effective chelators, pyridoxal isonicotinoyl hydrazone (PIH) and deferiprone (L1). Effective Fe chelation in the liver by PCTH was shown via its ability to reduce ferritin-(59)Fe accumulation. Mice treated for 3 weeks with PCTH at doses of 50 and 100 mg/kg/bd showed no overt signs of toxicity as determined by weight loss and a range of biochemical and haematological indices. In subchronic Fe excretion studies over 3 weeks, PIH and PCTH at 75 mg/kg/bd for 5 days/week increased faecal (59)Fe excretion to 140% and 145% of the vehicle control, respectively. This study showed that PCTH was well tolerated at 100 mg/kg/bd and induced considerable Fe excretion by the oral route, suggesting its potential as a candidate to replace DFO.     

HPLC determination of a novel aroylhydrazone iron chelator (o-108) in rabbit plasma and its application to a pilot pharmacokinetic study

A high performance liquid chromatographic method for the determination of a biocompatible iron chelator, pyridoxal 2-chlorobenzoyl hydrazone (o-108), in rabbit plasma was developed and validated. The separation was achieved on a C18 column with the mobile phase composed of a mixture of 0.01 M phosphate buffer (pH 6) with the addition of EDTA (2 mM), methanol and acetonitrile (42:24:14; v/v/v). The method was validated with respect to selectivity, linearity (0.8-150 microg/mL), intra- and inter-day variability and stability. This method was successfully applied to the analysis of the samples obtained from a pilot pharmacokinetic experiment, in which the chelator was administered intravenously to rabbits.     

Structure and biological properties of first row d-transition metal complexes with N-substituted sulfonamides

Cobalt (II), copper (II), nickel (II) and zinc (II) complexes with 2-hydroxy-1-naphthaldehyde derived N-substituted sulfonamides have been synthesized and the nature of bonding and structure of compounds have been deduced from physical, analytical and spectral (IR, ¹H NMR, ¹³C NMR, Mass and electronic) data. An octahedral geometry has been suggested for the complexes. Complexes along with the ligands were assessed for their antibacterial and antifungal activities on different species of pathogenic bacteria and fungi. The results revealed the ligands to possess moderate to significant antibacterial activity which was, in many cases, enhanced on chelation. Similar results were observed for antifungal activity. Brine shrimp bioassay was also carried out for in vitro cytotoxic properties against Artemia salina.     

New N-substituted hydrazones,derivatives of uridyl aldehyde

N-substituted isomeric hydrazones of uridyl aldehyde have been synthesized. The occurrence of the dominant E isomers with respect to the azomethine group was confirmed by means of NMR spectroscopy. Synthesized hydrazones feature an acetonide moiety as a protection of two hydroxyl groups on the ribose part. The attempt to remove the protecting group resulted in an azo-hydrazone tautomeric mixture. The described compounds may be valuable chiral ligands for metal chelation. Assessment of manganese(II) ion affinity to one selected hydrazone was performed.     

Cytotoxic iron chelators: characterization of the structure,solution chemistry and redox activity of ligands and iron complexes of the di-2-pyridyl ketone isonicotinoyl hydrazone (<Emphasis Type="Bold">H</Emphasis>PKIH) analogues

Di-2-pyridyl ketone isonicotinoyl hydrazone (HPKIH) and a range of its analogues comprise a series of monobasic acids that are capable of binding iron (Fe) as tridentate (N,N,O) ligands. Recently, we have shown that these chelators are highly cytotoxic, but show selective activity against cancer cells. Particularly interesting was the fact that cytotoxicity of the HPKIH analogues is maintained even after complexation with Fe. To understand the potent anti-tumor activity of these compounds, we have fully characterized their chemical properties. This included examination of the solution chemistry and X-ray crystal structures of both the ligands and Fe complexes from this class and the ability of these complexes to mediate redox reactions. Potentiometric titrations demonstrated that all chelators are present predominantly in their charge-neutral form at physiological pH (7.4), allowing access across biological membranes. Keto–enol tautomerism of the ligands was identified, with the tautomers exhibiting distinctly different protonation constants. Interestingly, the chelators form low-spin (diamagnetic) divalent Fe complexes in solution. The chelators form distorted octahedral complexes with Fe^II, with two tridentate ligands arranged in a meridional fashion. Electrochemistry of the Fe complexes in both aqueous and non-aqueous solutions revealed that the complexes are oxidized to their ferric form at relatively high potentials, but this oxidation is coupled to a rapid reaction with water to form a hydrated (carbinolamine) derivative, leading to irreversible electrochemistry. The Fe complexes of the HPKIH analogues caused marked DNA degradation in the presence of hydrogen peroxide. This observation confirms that Fe complexes from the HPKIH series mediate Fenton chemistry and do not repel DNA. Collectively, studies on the solution chemistry and structure of these HPKIH analogues indicate that they can bind cellular Fe and enhance its redox activity, resulting in oxidative damage to vital biomolecules.Electronic Supplementary Material Supplementary material is available in the online version of this article at .Abbreviations DFO desferrioxamine - HPKIH di-2-pyridyl ketone isonicotinoyl hydrazone - HNIH 2-hydroxy-1-naphthaldehyde isonicotinoyl hydrazone - HPCIH 2-pyridinecarbaldehyde isonicotinoyl hydrazone - HPIH pyridoxal isonicotinoyl hydrazone - L linear DNA - OC open circular DNA - SC supercoiled DNA     

A requirement for chelation in obtaining functional chloroplasts of sunflower and wheat.

In studying conditions for obtaining photosynthetically functional chloroplasts from mesophyll protoplasts of sunflower and wheat, a strong requirement for chelation was found. The concentration of chelator, either EDTA or pyrophosphate (PP_i), required for maximum activation depended on the pH, the concentration of orthophosphate (P_i) in the assay, and the chelator used. Studies with EDTA indicate that including the chelator in the isolation, resuspension, and assay media, in the absence of divalent cations, was most effective. Increased concentration of EDTA from 1 to 10 mm broadened the pH response curve for photosynthesis, inasmuch as a higher concentration of chelator was required for activation of photosynthesis at lower pH.Either EDTA, PP_i, or citrate could activate photosynthesis of sunflower chloroplasts isolated and assayed at pH 8.4. At pH 7.6, PP_i and EDTA were equally effective at low P_i concentrations but PP_i was particularly effective in shortening the induction period at high concentrations of P_i (2.5 mm) in the assay medium. Including 1 mm 3-phosphoglycerate in the assay medium with or without P_i could not replace the need for chelation. However, 3-phosphoglycerate + EDTA in the assay medium with 0.5 mm P_i, pH 7.6, gave a short induction period and rates of photosynthesis similar to those with 10 mm PP_i. The results suggest that PP_i can have a dual effect at the lower pH through chelation and inhibition of the phosphate transporter.Photosynthesis by sunflower chloroplasts isolated and assayed at pH 8.4 with 0.2 mm EDTA (+ 0.5 mm P_i in the assays) was severely inhibited by 2 mM CaCl₂, MgCl₂, or MnCl₂. Wheat chloroplasts isolated and assayed at pH 8.4 without chelation, and assayed with 0.2 mm P_i, had low rates of photosynthesis (25 μmol O₂ evolved mg^?1 chlorophyll h^?1) which were strongly inhibited by 2 to 4 mm MgCl₂, MnCl₂, or CaCl₂. With inclusion of EDTA and P_i at optimum levels, isolated chloroplasts of sunflower and wheat have high rates of photosynthesis and PP_i or divalent cations are not of benefit.     

19F nuclear magnetic resonance studies of free calcium in heart cells.

19F nuclear magnetic resonance is used in conjunction with 5,5'-difluoro-1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBapta), a fluorinated calcium chelator, to report steady-state intracellular free calcium levels ([Ca2+]i) in populations of resting, quiescent, isolated adult heart cells. 31P nuclear magnetic resonance shows that 5FBapta-loaded cells maintain normal intracellular high-energy phosphates, pH, and free Mg2+. The intracellular free calcium concentration of well perfused, isolated heart cells is 61 +/- 5 nM, measured with 5FBapta, which has a dissociation constant (Kd) for calcium chelation of 500 nM. A similar value is obtained with Quin-MF, another fluorinated calcium chelator with Kd and maximum calcium sensitivity at 80 nM. We find that the steady-state level of intracellular free calcium is increased by decreased extra-cellular sodium concentration, omission of extracellular magnesium, decreased extracellular pH, hyperglycemia, and upon treatment with lead acetate. Further, extracellular ATP caused a large transient increase in [Ca2+]i. Thus, while heart cells maintain a very low level of intracellular free Ca2+, acute alterations in extracellular environment can cause derangement of calcium homeostasis, resulting in measurable increases in [Ca2+]i.     

Effect of cations,including heavy metals,on cadmium uptake by Lemna polyrhiza L.

Cations, including calcium, magnesium, potassium, sodium, copper, iron, nickel and zinc, inhibited (up to 40%) extracellular binding and intracellular uptake of cadmium by Lemna polyrhiza in solution culture. Test plants showed a high capacity of extracellular cadmium binding which was competitively inhibited by copper, nickel and zinc; however, calcium, magnesium and potassium caused non-competitive inhibition. Iron and sodium increased K _m and decreased V _max, thereby causing mixed inhibition of extracellular binding. Intracellular cadmium uptake displayed Michaelis-Menten kinetics. It was competitively inhibited by calcium, magnesium, iron, nickel and zinc. Monovalent cations (sodium and potassium) caused non-competitive and copper caused mixed inhibition of intracellular cadmium uptake. Thus, high levels of cations and metals in the external environment should be expected to lower the cadmium accumulation efficiency of L. polyrhiza.     

The cellular transport of calcium in rat liver

The bidirectional transport of calcium in rat liver was studied using slices labeled with Ca⁴⁷ in a closed two compartment system. Steady-state conditions were observed with influx and efflux transfer coefficients of 0.070 and 0.018 per minute, respectively. The rapidly exchanging cell fraction of calcium existed at a concentration three times higher than the average cell concentration of calcium and occupied cell loci comprising less than 25% of the cell mass, suggesting that calcium associated with the cell membranes, nuclei, and mitochondria participated in the rapidly exchanging fraction. At pH 7.4 and 377deg;C, the influx transfer coefficient was 25% above the steady-state condition and accumulation of calcium by the slices occurred. Studies of the effects of varied physical and chemical conditions revealed that the influx transfer coefficient was increased by elevated pH, strontium, certain metabolic inhibitors, and 2 mM concentrations of cyclic adenosinemonophosphate and adenosinetriphosphate. The influx transfer coefficient was decreased by reduced temperature, decreased pH, magnesium, and 10 mM adenosinetriphosphate. The efflux transfer coefficient was increased by elevated pH, strontium, iodoacetate, and adenosinetriphosphate, and was decreased by reduced temperature and by N-ethylmaleimide. These data support the thesis that cell transport of calcium is accomplished by the attachment of calcium atoms to the cell surface and transport through the plasma membrane bound to either specific carriers or to membrane constituents. Conditions which change the affinities, capacities, and mobilities of plasma membrane ligands that bind calcium or cause extracellular chelation of calcium are capable of altering the rate of calcium transport.     

In vitro modulation of filament bundling in f-actin and keratins by annexin II and calcium

Summary In our preliminary subcellular localization experiment we demonstrated that annexin II co-localized with submembranous actin in subpopulations of both cultured fibroblasts and keratinocytes. To investigate the physical interaction between annexin II and actin at the cell periphery, in vitro reconstitution experiments were carried out with keratins used as a control. Annexin II, isolated by immunoaffinity column chromatography, was found to exist as globular structures measuring 10 to 25 nm in diameter by rotary shadowing, similar to a previous report. We believe that these structures represent its polymeric forms. By negative staining, monomeric annexin II was detectable as tapered rods, measuring 6 nm in length and 1 to 2 nm in diameter. When annexin II was mixed with actin in 3 mM piperazine-N, N-bis-2-ethanesulfonic acid (PIPES) buffer with 10 mM NaCl₂, 2 mM MgCl₂ and 0.1 mM CaCl₂, thick twisting actin bundles formed, confirming previous reports. This bundling was much reduced when calcium was removed. In the presence of 5 mM ethylenediamine tetra-acetic acid (EDTA) in 5 mM tris, pH 7.2, keratins were found to form a network of filaments, which began to disassemble when the chelator was removed and became fragmented when 0.1 mM CaCl₂ was added. Keratins under the same conditions did not fragment when annexin II was present. These results suggest that annexin II, in conjunction with Ca²⁺, may be involved in a flexible system accommodating changes in the membrane cytoskeletal framework at the cell periphery in keratinocytes.     

Serum Zinc, Copper, Selenium, Calcium, and Magnesium Levels in Pregnant and Non-Pregnant Women in Gondar, Northwest Ethiopia

Pregnant women in developing countries are vulnerable to multiple micronutrient deficiencies. Studies assessing serum levels of the micronutrients and magnitude of their deficiencies are very scarce in African subjects. This study was aimed at determining serum levels of micronutrients in 375 pregnant (42 HIV seropositive) and 76 non-pregnant women (20 HIV seropositive) who visited the University of Gondar Hospital, Gondar, Ethiopia. Serum concentrations of zinc,\ copper, selenium, calcium, and magnesium were determined using an inductively coupled plasma mass spectrometer. Irrespective of HIV serostatus, pregnant women had significantly higher serum concentrations of copper and copper/zinc ratio and significantly lower magnesium compared to those in non-pregnant women (P < 0.05). Except for selenium, which was significantly lower in HIV-seropositive pregnant women (P < 0.05), the mean serum concentrations of zinc, copper, calcium, and magnesium were not significantly different between pregnant women by HIV serostatus. The prevalence of deficiency in zinc, magnesium, selenium, and calcium in the pregnant women, irrespective of their HIV serostatus, was 66.7%, 25.6%, 21.9%, and 9.3%, respectively. The magnitude of deficiency in zinc, magnesium, and selenium was significantly higher in HIV seropositive pregnant women (76.2%, 52.4%, and 45.2%) than that in HIV-seronegative pregnant women (65.5%, 22.2%, and 18.9%) and in HIV-seronegative non-pregnant women (42.9%, 8.1%, and 30.4%; P < 0.05). Deficiency in one, two, three, or four mineral elements was observed in 44.8%, 14.4%, 9.9%, and 5.1% of the pregnant women, respectively. Only 25.9% of the pregnant women and 44.7% of the non-pregnant women were not deficient in any of the micronutrients. The high prevalence of micronutrient deficiencies in pregnant and non-pregnant women in Gondar, Ethiopia warrants the need for strategies on prevention and control of the deficiencies.     

Partition coefficients of the iron(III) complexes of pyridoxal isonicotinoyl hydrazone and its analogs and the correlation to iron chelation efficacy

Pyridoxal isonicotinoyl hydrazone and its analogs are orally effective Fe(III) chelators which show potential as drugs to treat iron overload disease. The present investigation describes the measurement of the partition coefficient of the apochelator and Fe(III) complex of 20 of these ligands. These measurements have been done to investigate the relationship between lipophilicity and the efficacy of iron chelation in rabbit reticulocytes loaded with non-heme ⁵⁹Fe. The results demonstrate a linear relationship between the partition coefficient (P) of the apochelator and its Fe(III) complex, and a simple equation has been derived relating these two parameters. Experimental data in the literature are in agreement with the equation. The relationship of the partition coefficients of the iron chelators and of their Fe(III) complexes to the effectiveness of the ligands in mobilizing iron in vitro and in vivo is also discussed.     

Calcium,magnesium, and zinc status of young adult females on an adequate protein and calorie intake

Calcium, magnesium, and zinc balances were determined in eleven young adult college females (mean age, 24.9±2.35) during a 39-d metabolic study when the subjects were fed an adequate calorie and protein diet based on habitually consumed foods. Analysis showed that the dietary contribution of calcium, magnesium, and zinc to the RDA were 53.6, 26.4, and 57.9%, respectively. Mean fecal losses of calcium and magnesium were low, while fecal zinc losses were higher than the daily intake. Mean urinary excretion of calcium was within the normal range, but was low for magnesium whereas urinary zinc was higher than normal. Mean daily apparent retentions of calcium and magnesium were positive, whereas positive apparent retention for zinc were observed in four of the subjects. Plasma calcium and magnesium remained normal, but mean plasma zinc declined at the end of the study. Significant correlations were observed between the fecal losses of calcium and magnesium and calcium and zinc. Urinary calcium also correlated significantly (P<0.05) with urinary magnesium, but not with zinc. It appears that adequate protein and calorie intake in the presence of low dietary intake of calcium, magnesium, and zinc has no significant effect on calcium and magnesium status whereas a lowering effect on plasma zinc and apparent zinc retention was observed in the subjects studied.     

复合疲劳对大鼠不同组织矿物质代谢影响研究

目的:研究复合疲劳大鼠血液、肌肉、肝脏和脑中矿物元素代谢变化的影响。方法:将30只大鼠随机分为正常对照组、食物限制组和复合疲劳组。经过5天的实验干预后,提取动物的血液、腓肠肌、肝脏和脑,并利用原子吸收分光光度法测量各组织中的钾(K)、钙(Ca)、镁(Mg)、铁(Fe)、锌(Zn)和铜(Cu)。结果:相对正常对照组和食物限制组,复合疲劳大鼠的肌肉、肝脏和脑中的K(P<0.01)和肝脏中的Fe(P<005)明显升高,血液中的Cu(与正常对照组比较P<0.01,与食物限制组比较P<0.05)明显下降;与对照组相比,复合疲劳大鼠的血液中的K明显升高(P<0.05),血液中的Mg和Zn(P<0.05),肌肉中的Ca、Mg和Zn(PCa<0.05,PMg<0.05,PZn<0.01),肝脏中的Ca和Zn(PCa<0.01,PZn<0.05),以及脑中的Fe、Mg和Zn(PFe<0.05,PMg<0.05,PZn<0.01)明显降低。结论:在复合疲劳状态下,大鼠血液、肌肉、肝脏和脑中的K、Ca、Mg、Fe、Zn和Cu代谢发生变化,可能在疲劳的发生与缓解中发挥作用。