Biomedical subjects

Jun Li

Publications and source records attributed to Jun Li.

At least 199 records · Page 11Linked to original sources

PubMed2006

[Determination of T-2 toxin in cereal grains by high performance liquid chromatography with fluorescence detection after immunoaffinity column clean-up and precolumn derivatization].

A method has been developed for the determination of T-2 toxin in cereal grains by high performance liquid chromatography with fluorescence detection after immunoaffinity column clean-up and precolumn derivatization. The derivatization reaction was used to develop a sensitive, reproducible and accurate method for the determination of T-2 toxin in wheat, corn, barley and rice. T-2 toxin was extracted with methanol-water (80: 20, v/v), purified by immunoaffinity columns containing antibodies specific for T-2 toxin, and quantified by reversed-phase high performance liquid chromatography with fluorescence detection (excitation wavelength, 381 nm; emission wavelength, 470 nm) after derivatization with 1-anthroylnitrile (1-AN) and 4-dimethylaminopyridine (DMAP). ZORBAX Eclipse XDB-C18 column and mobile phase of acetonitrile-water (80: 20, v/v) were used for the analysis. Recoveries from the different cereals spiked with T-2 toxin at levels ranging from 0.01 to 1.5 microg/g were from 79.7% to 94.5%, the relative standard deviations were lower than 7% and the limit of detection was 0.01 microg/g based on a signal-to-noise ratio of 3: 1.

Acetonitriles↗

PubMed2006

[Study on chemical constituents of Cyclocarya paliurus].

Phytochemical investigation of chemical constituents of the CHCl3 fraction of 75% alcohol extract from the leaves of Cyclocarya paliurus has resulted in the isolation of five compounds, alpha-boswellic (I), beta-boswellic (II), Oleanolic acid (III), 4-hydroxyl-3-methoxyl-benzoic acid (IV) and 3,6,3',5'-tetramenthox-5,7,4'-trihydroxy-flavonol (V). Their structures were elucidated on the basis of spectroscopic analyses, especially NMR. Compunds I, II, IV and V were obtained from this plant for the first time.

Juglandaceae↗

PubMed2006

[Study on chronical hepatitis B with treatment of integrative traditional Chinese and Western medicine].

OBJECTIVE: To study curative effect of chronical hepatitis B with treatment of integrative traditional Chinese and western medicine. METHOD: 115 cases of HBeAg and/or HBVDNA positive chronical hepatitis B were randomly divided into two groups in control. The first group treated by traditional Chinese medicine (TCM)-Fufang Huangqi granule and the second treated by intergrative traditional Chinese and western medicine (ICWM)-Fufang Huangqi granule and lamivudine for at least 24 weeks. RESULT: The positive rate of HBVDNA at 12, 24 weeks, and the positive rate of HBeAg at 24 weeks in TCM are markedly lower than those of before treatment (P < 0.01). The positive rate of HBeAg and the positive rate of HBVDNA in ICWM are markedly lower than those of before treatment both at 12, 24 weeks (P < 0.01). The average values of HBVDNA are markly lower than before treatment in two groups at both 12,24 weeks (P < 0.01). At 12 weeks, the negative-turning rate of HBVDNA in the ICWM group is 79.17%, which shows significant difference in comparision with 40.00% in the TCM group (P < 0.01). The negative-turning rate of HBeAg in the ICWM group is 26.92%, which shows no significant difference in comparision with 32. 08% in the TCM group. At 24 weeks, the negative-turning rate of HBVDNA in the ICWM group is 85.71%, which shows significant difference in comparision with 50.00% in the TCM group (P < 0.01). The negative-turning rate of HBeAg in the ICWM group is 36.36%, which shows no significant difference in comparision with 28.57% in the TCM group. At 12 weeks,the total effective rate of the ICWM group is 96. 43%, which shows significant difference in comparision with 71.26% in the TCM group (P<0.01). At 24 weeks, the total effective rate of the ICWM group is 88. 00%, which shows significant difference in comparision with 67.61 % in the TCM group (P < 0.01). The average values of ALT and AST are markly improved than those of before treatment in two groups (P < 0.01). The average values of ALB is markly higher than before in TCM groups after 24 weeks treatment (P < 0.01). CONCLUSION: Fufang Huangqi granule integrated with lamivudine possesses a better effect for counteracting the hepatitis B virus and improving the liver functioin than only itself.

Adolescent↗

PubMed2006

[Protective effects of recombinant intestinal trefoil factor against intestinal injuries induced by endotoxin in young rats].

OBJECTIVE: This study aimed to investigate the protective effects of recombinant intestinal trefoil factor (rITF) against intestinal injuries and the possible mechanism by examining the changes of diamine oxidase (DAO) and TNF-alpha and the intestinal ultrastructural changes in lipopolysaccharide (LPS) induced intestinal injuries. METHODS: Ninety-six ten-day-old Wistar rats were randomly injected with either normal saline (1 mL/kg, Control group), LPS (1 mL/kg) or LPS (1 mL/kg) + rITF (0.1 mL) intraperioneally. At 2, 6, 24 and 72 hrs after administration plasma DAO activity was determined using absorption spectrometry; and the intestinal protein and mRNA expression of TNF-alpha were measured using immunohistochemistry and RT-PCR methods. The intestinal ultrastructural changes were observed by electron microscopy. RESULTS: The plasma DAO activity in the LPS group began to increase at 2 hrs, peaked at 6 hrs and remained at significantly higher levels until 72 hrs after administration compared with the Control group (P < 0.01). The plasma DAO activity in the LPS + rITF group decreased noticeably compared with the LPS group at all time points (P < 0.01 or 0.05). A significant difference in the plasma DAO activity was only observed at 6 hrs after administration between the LPS + rITF and the Control group. The expression of TNF-alpha protein in the LPS group significantly increased at each time point, peaking at 6 hrs after LPS administration, with the IODT of TNF-alpha of 37,247.64 +/- 3,387.59 vs 6,191.02 +/- 482.32 (P < 0.01) compared with the Control group. rITF treatment decreased the expression of TNF-alpha protein although it remained significantly higher than in the Control group (P < 0.01). The TNF-alpha mRNA was weakly expressed in the Control group but strikingly increased after LPS injection (P < 0.01). Compared with the LPS group, the TNF-alpha mRNA expression in the LPS + rITF group decreased at all time points (P < 0.01 or 0.05). Vacuole changes of mitochodrium, cell nucleus condense, break and depletion of part of microvilli, and widen and disrupted tight junction were observed in the LPS group. The ultrastructural changes of intestinal tissues were improved in the LPS + rITF group. CONCLUSIONS: rITF can decrease the plasma DAO activity and inhibit the expression of TNF-alpha, resulting in a protective effect against intestinal injuries induced by LPS in young rats.

Amine Oxidase (Copper-Containing)↗

PubMed2006

Removal of organic matter and nitrogen from distillery wastewater by a combination of methane fermentation and denitrification/nitrification processes.

The distillery wastewater of Guangdong Jiujiang Distillery, which is characteristic of containing high organic matters and rich total nitrogen, was treated by a combination of methane fermentation and denitrification/nitrification processes. 80% of COD in the raw wastewater was removed by methane fermentation at the COD volumetric loading rate of 20 kg COD/(m3 x d) using the expanded granule sludge bed (EGSB) process. However, almost all the organic nitrogen in the raw wastewater was converted into ammonia by ammonification there. Ammonia and volatile fatty acids (VFA) remaining in the anaerobically treated wastewater were simultaneously removed utilizing VFA as an electron donor by denitrification occurring in the other EGSB reactor and nitrification using PEG-immobilized nitrifying bacteria with recirculation process. An aerobic biological contact oxidization reactor was designed between denitrification/nitrification reactor for further COD removal. With the above treatment system, 18000-28000 mg/L of COD in raw wastewater was reduced to less than 100 mg/L. Also, ammonia in the effluent of the system was not detected and the system had a high removal rate for 900-1200 mg/L of TN in the raw wastewater, only leaving 400 mg/L of nitrate nitrogen.

Ammonia↗

PubMed2006

[Cardiac valve MCSF-1 and its receptor expression changes in Staphylococcus aureus induced infective endocarditis].

OBJECTIVE: To explore the cellular immunology mechanism of infective endocarditis (IE), we investigated the effects of Staphylococcus aureus (S. aureus) on MCSF-1 and its receptor (c-fms) gene expression in cardiac valves. METHODS: Thirty-two rabbits were divided into 4 groups: mitral or tricuspid valve artificial lesions with 5 x 10(4) CFU or 5 x 10(6) CFU S. aureus injection. Control rabbits (n = 7) received 5 x 10(6) CFU S. aureus injection. IE after operation were confirmed by naked eyes and electron microscope observations. MCSF-1, c-fms in mitral and tricuspid valves were detected by RT-PCR. RESULTS: Twenty-six rabbits survived the operation and 14 rabbits developed IE (2 with 5 x 10(4) CFU and 12 with 5 x 10(6) CFU S. aureus injection) one day post operation. S. aureus injection alone did not induce IE. Compared to control rabbits, MCSF-1 mRNA was significantly upregulated and c-fms mRNA significantly downregulated after 5 x 10(4) CFU S. aureus injection with heart valve artificial lesion in mitral valves or tricuspid valves. MCSF-1 expression in mitral valves was further increased while remained unchanged in tricuspid valve after 5 x 10(6) CFU S. aureus injection compared to that in 5 x 10(4) CFU S. aureus injection group. CONCLUSION: High dose bacterial invasion and heart valves lesion were the main factors for inducing infective endocarditis. Development of infective endocarditis was associated with valve MCSF-1/c-fms expression changes in this rabbit model.

Animals↗

PubMed2006

[Differential expression of extracellular matrix metalloproteinase inducer in normal placenta and preeclampsia placenta].

OBJECTIVE: To study the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in preeclampsia placenta and the relation with preeclampsia attacks. METHODS: Forty-four samples from pregnant women with preeclampsia (preeclampsia group), 38 samples from pregnant women with eclampsia, and 49 samples from normal pregnancies (control group) were obtained. We detected the expression of EMMPRIN in placenta by immunohistochemistry and the expression of EMMPRIN mRNA by RT-PCR. RESULTS: (1) EMMPRIN positive expression: in preeclampsia group, the moderate expression rate was 18% (8/44) and the strong positive rate was 9% (4/44); in eclampsia group moderate positive rate was 21% (8/38) and strong positive rate 13% (5/38). The difference of the two groups was insignificant (P > 0.05). In control group the moderate positive rate was 12% (6/49) and strong positive rate 82% (40/49), the difference from the preeclampsia and the eclampsia groups was significant (P < 0.001). (2) EMMPRIN mRNA expression: in preeclampsia group EMMPRIN mRNA expression in term placenta (37 - 40 gestational weeks) was 0.342 +/- 0.002, and in eclampsia group 0.344 +/- 0.023; the difference between the two groups was insignificant (P > 0.05). In control group EMMPRIN mRNA expression in term placenta (37 - 40 gestational weeks) was 0.872 +/- 0.094, the differences between the control group and preeclampsia and eclampsia groups were both significant (P < 0.001). CONCLUSION: The decrease in the expression of EMMPRIN in placenta is an important cause of preeclampsia onset; expression rate of EMMPRIN may serve as an indicator in predicting preeclampsia.

Adult↗

PubMed2006

[An analysis of 276 cases of drug-induced liver damage].

OBJECTIVE: Drug-induced liver damage is a potential complication from using many drugs. The aim of our study was to analyze the etiology and clinical features of drug-induced liver damage, in order to draw more attention to this problem. METHODS: Two hundred and seventy-six cases over a 5-year period in Jiangsu Province Hospital were retrospectively analyzed. RESULTS: A variety of drugs, including traditional Chinese medicines (26.1% of our total cases) and anticancer drugs (17%) caused liver damage. The main clinical manifestations of it were fatigue, nausea, vomiting and jaundice. In 88% of our cases the symptoms were relieved or completely disappeared, but there was still a 5.1% mortality rate. CONCLUSIONS: The clinical features of drug-induced liver damage are of no specificity, and the mortality of it is not low. Liver function should be monitored when suspected drugs are prescribed.

Adolescent↗

PubMed2006

[Surgical treatment for tumors of trachea, carina and main bronchus].

OBJECTIVE: To review the experience in surgical treatment for tumors of trachea, carina and main bronchus. METHODS: From Jan. 1996 to Jun. 2004, 27 patients with tumor of trachea, carina or main bronchus underwent surgery including resection and reconstruction of trachea in 8, right/left pneumonectomy and carinal resection and reconstruction in 9 (6/3), right sleeve upper lobectomy and carnial resection with reconstruction of trachea and carina in 2, carina resection and reconstruction in 3, tumor removal through tracheal windows in 5. CPB (cardiopulmonary bypass) was used in 2 patients during surgery. RESULTS: There were 3 peri-operative deaths caused by acute respiratory failure in 2 and severe postoperative bleeding in 1 case. After follow-up of more than 6 months, no death or post-operative complication occurred. CONCLUSION: Resection and reconstruction for patients with tumor of trachea, main bronchus or carina can be performed with excellent results using effective surgical and anaesthetic methods with or without CPB assistance.

Adenocarcinoma↗

PubMed2006

[Establishment of model with inner ear mimetic aging and mtDNA 4834 bp deletion in rats].

OBJECTIVE: To explore the establishment of the mimetic aging effect in the inner ear of the rat. METHOD: Twenty-four Wistar rats were randomly divided into two groups: group A (D-galactose group, n = 14), which were treated with hypodermic 5% D-galactose (150 mg x kg(-1) x d(-1)) for 8 weeks and then with intraperitoneal saline for 10 days, and group B (control group, n = 10), which were given saline only. Auditory brainstem response(ABR) was used to detect the hearing threshold of rats, and colorimetry was used to analyze the activity of the glutathione peroxidase (GSH-PX). The inner ear tissue was harvested and mitochondrial DNA was amplified to identify the 4 834 bp deletion mutation by nested primer polymerase chain reaction (nested PCR) technique. RESULT: The incidence of mitochondrial DNA 4 834 bp deletion of group A was 100% (28/28), while the deletion of group B was 0. The activity of the GSH-PX in group A (59.07 +/- 8.70 U) was lower than that in group B (142.10 +/- 7.02 U). The difference between group A and group B was significant (t-test, P < 0.01). Variation in ABR threshold of (5.36 +/- 3.08) dB peSPL was observed in group A, and (6.50 +/- 3.37) dB peSPL in group B. The difference in shift of ABR threshold between group A and group B was not significant (P > 0.05). CONCLUSION: The mimetic aging effect in the inner ear of the rat can be induced by D-galactose, and this rat model presents high incidence of mtDNA4834 deletion. But no hearing loss was found in this model.

Aging, Premature↗

PubMed2006

[A clinical study of adefovir dipivoxil, made in China, for treatment of hepatitis B e antigen-positive patients with chronic hepatitis B].

OBJECTIVE: To evaluate the efficacy and safety of a China made adefovir dipivoxil (ADV) treatment for hepatitis B e antigen-positive patients with chronic hepatitis B. METHODS: Two hundred and thirty patients with chronic hepatitis B who were positive for hepatitis B e antigen (HBeAg) were randomly put into groups A or B, and 58 patients with lamivudine-resistant chronic hepatitis B were randomly put into groups C or D. During the first 12 weeks of the trial, 112 patients in group A and 115 patients in group B received 10 mg of ADV and a placebo once a day; 28 patients in group C received 100 mg of lamivudine (LMV) and 10 mg of ADV; 29 patients in group D received 100 mg of LMV and a placebo once a day. In the second trial period, all patients received ADV for 36 weeks. The primary checking criterion was the serum HBV DNA change during the treatment. The secondary ones were alanine aminotransferase (ALT) normalization, HBeAg loss, and HBeAg seroconversion. RESULTS: At week 12, the median serum hepatitis B virus (HBV) DNA level of group A (ADV-ADV) was reduced 2.8 log10 copies/ml, significantly greater than that of group B (placebo-ADV) of 0.3 log10 copies/ml reduction (P = 0.000). At week 48, the median serum HBV DNA level of group A and group B were reduced 3.6 and 3.4 log10 copies/ml respectively. At week 12, the median serum HBV DNA level of group C (LMV+ADV) was reduced 3.0 log10 copies/ml, significantly greater than that of the group D (LMV+placebo) of 0.16 log10 copies/ml reduction (P = 0.000). At week 48, the median serum HBV DNA level of group C and group D were reduced 3.6 and 3.8 log10 copies/ml respectively. Only 5.56% (16/288) patients had adverse events that were mild to moderate. There was no significant difference in the change of serum creatinine compared with their baseline levels. CONCLUSION: In our HBeAg positive lamivudine-resistant chronic hepatitis B patients, 48 weeks of ADV treatment was safe and resulted in significant virological and biochemical improvements.

Adenine↗

PubMed2005

Electronic structure differences in ZrO2 vs HfO2.

Although ZrO2 and HfO2 are, for the most part, quite similar chemically, subtle differences in their electronic structures appear to be responsible for differing MO2/Si (M = Zr, Hf) interface stabilities. To shed light on the electronic structure differences between ZrO2 and HfO2, we have conducted joint experimental and theoretical studies. Because molecular electron affinities are a sensitive probe of electronic structure, we have measured them by conducting photoelectron spectroscopic experiments on ZrO2(-) and HfO2(-). The adiabatic electron affinity of HfO2 was determined to be 2.14 +/- 0.03 eV, and that of ZrO2 was determined to be 1.64 +/- 0.03 eV. Concurrently, advanced electronic structure calculations were conducted to determine electron affinities, vibrational frequencies, and geometries of these systems. The calculated CCSD(T) electron affinities of HfO2 and ZrO2 were found to be 2.05 and 1.62 eV, respectively. The molecular results confirm earlier predictions from solid state calculations that HfO2 is more ionic than ZrO2. The excess electron in MO2(-) occupies an sd-type hybrid orbital localized on the M atom (M = Zr, Hf). The structural parameters of ZrO2 and HfO2 and their vibrational frequencies were found to be very similar. Upon the excess electron attachment, the M-O bond length increases by ca. 0.04 A, the OMO angle increases by 2-4 degrees, and frequencies of all vibrational modes become smaller, with the stretching modes being shifted by 30-50 cm(-1) and the bending mode by 15-25 cm(-1). Together, these studies unveil significant differences in the electronic structures of ZrO2 and HfO2 but not in their structural or vibrational characteristics.

Journal Article↗

PubMed2005

An association study between the transthyretin (TTR) gene and mental retardation.

It is known that in the pathogenesis of mental retardation (MR), both genetic and environmental factors (particularly iodine deficiency) appear to play a critical role. Transthyretin (TTR) transports between 20% and 30% of serum thyroxine in normal individuals and it is the main T(4)-binding protein in CSF. Variability in the TTR gene may influence risk for iodine-deficiency-based MR. The SNPs we selected from dbSNP were detected and identified using ARMS-PCR and sequencing methods, and we identified five novel sequence variants. Singular-locus association analysis indicated no association between the TTR gene and MR. In haplotype analysis, however, we found a haplotype CGTG+ (rs723744/G+6649C/T+6690C/rs2276382/del9) showed a weak positive association with MR (chi(2) = 6.699, p = 0.035). Finally, we concluded that the weak positive result is more likely to be due to sampling error and the small size of this haplotype resulting from its relative low frequency. Our negative results provide no evidence that variants of TTR gene influence susceptibility to MR in the iodine-deficient areas of China and suggest that there may be a compensatory mechanism(s) in humans and mice, which work(s) to compensate the effect of mutation in the TTR gene on MR.

Child↗

PubMed2005

Chemiluminescence of CdTe nanocrystals induced by direct chemical oxidation and its size-dependent and surfactant-sensitized effect.

CdTe nanocrystals (NCs) capped with thioglycolic acid (TGA) were synthesized via a microwave-assisted method. The chemiluminescence (CL) of CdTe NCs induced by directly chemical oxidation and its size-depended and surfactant-sensitized effect in aqueous solution were then investigated. It was found that oxidants, especially hydrogen peroxide and potassium permanganate, could directly oxidize CdTe NCs to produce strong CL emission in basic conditions. The oxidized CL of CdTe NCs displayed size-dependent effect and its intensity increased along with increasing the sizes of the NCs. Moreover, the CL intensity could, if surfactants CTAB or beta-cyclodextrin were added to the above CL system, be sensitized to some degree. The sensitized CL induced by CTAB and beta-cyclodextrin is mainly contributing to the formation of aggregate nanostructure and the micellar micronanoenvironment, respectively. The possible oxidized CL mechanisms were further examined by means of photoluminescence spectra, CL spectra, and transmission electron microscopy studies. The CL properties of CdTe NCs not only will be helpful to study physical chemistry properties of semiconductor nanocrystals but also are expected to find use in many fields such as luminescence devices, bioanalysis, and multicolor labeling probes.

Journal Article↗

PubMed2005

Anti-oxidative effect of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. leaf in chronic bronchitis rats.

The study was to evaluate the effect of triterpene acids of Eriobotrya japonica (Thunb.) Lindl. leaf (TAL) on expression of antioxidative mediators by alveolar macrophages (AM) in rats with chronic bronchitis (CB), CB was induced by endotracheal instillation of lipopolysaccharedes (LPS) followed by Bacillus Calmette-Guérin (BCG) injection through caudal vein 1 week later. Treatment groups received TAL at there different doses (50, 150, or 450 mg/kg daily, intragastrically (i.g.)) or dexamethasone (1.2 mg/kg daily i.g.) for 2 weeks, 7 days after LPS injection. AM were then isolated and incubated. Superoxide dismutase (SOD) and methylene dianiline (MDA) levels in AM were measured by commercial kits; meanwhile, heme oxygenase-1 (HO-1) expression and its mRNA expression in AM were detected by immunocytochemistry and RT-PCR, respectively. HO-1 activity of the lung was also detected by a specific biochemistry reaction. The levels of MDA and HO-1 expressed by cultured AM and the HO-1 activity in the lung of the TAL groups were significantly lower than those from the CB group without treatment (p < 0.01 and p < 0.05, respectively), while the SOD levels were increased in a dose-dependent manner by TAL treatment. These results suggest that TAL inhibits HO-1 expression and MDA production and up-regulates SOD expression in AM from CB rats, which might be one of molecular mechanisms of its anti-inflammatory effects in CB rats.

Administration, Oral↗

PubMed2005

Tyrosine phosphatase MEG2 modulates murine development and platelet and lymphocyte activation through secretory vesicle function.

MEG2, a protein tyrosine phosphatase with a unique NH2-terminal lipid-binding domain, binds to and is modulated by the polyphosphoinositides PI(4,5)P2 and PI(3,4,5)P3. Recent data implicate MEG2 in vesicle fusion events in leukocytes. Through the genesis of Meg2-deficient mice, we demonstrate that Meg2-/- embryos manifest hemorrhages, neural tube defects including exencephaly and meningomyeloceles, cerebral infarctions, abnormal bone development, and >90% late embryonic lethality. T lymphocytes and platelets isolated from recombination activating gene 2-/- mice transplanted with Meg2-/- embryonic liver-derived hematopoietic progenitor cells showed profound defects in activation that, in T lymphocytes, was attributable to impaired interleukin 2 secretion. Ultrastructural analysis of these lymphocytes revealed near complete absence of mature secretory vesicles. Taken together, these observations suggest that MEG2-mediated modulation of secretory vesicle genesis and function plays an essential role in neural tube, vascular, and bone development as well as activation of mature platelets and lymphocytes.

Animals↗

PubMed2005

TWEAK attenuates the transition from innate to adaptive immunity.

Innate immunity is the first line of defense against infection, protecting the host during the development of adaptive immunity and critically affecting the nature of the adaptive response. We show that, in contrast to tumor necrosis factor alpha (TNF-alpha), the related protein TWEAK attenuates the transition from innate to adaptive mechanisms. TWEAK-/- mice had overabundant natural killer (NK) cells and displayed hypersensitivity to bacterial endotoxin, with their innate immune cells producing excess interferon (IFN)-gamma and interleukin (IL)-12. TWEAK inhibited stimulation of the transcriptional activator STAT-1 and induced p65 nuclear factor (NF)-kappaB association with histone deacetylase 1, repressing cytokine production. TWEAK-/- mice developed oversized spleens with expanded memory and T helper 1 (TH1) subtype cells upon aging and mounted stronger innate and adaptive TH1-based responses against tumor challenge. Thus, TWEAK suppresses production of IFN-gamma and IL-12, curtailing the innate response and its transition to adaptive TH1 immunity.

Animals↗

PubMed2005

Intermittent hypoxia protects cardiomyocytes against ischemia-reperfusion injury-induced alterations in Ca2+ homeostasis and contraction via the sarcoplasmic reticulum and Na+/Ca2+ exchange mechanisms.

We have previously demonstrated that intermittent high-altitude (IHA) hypoxia significantly attenuates ischemia-reperfusion (I/R) injury-induced excessive increase in resting intracellular Ca(2+) concentrations ([Ca(2+)](i)). Because the sarcoplasmic reticulum (SR) and Na(+)/Ca(2+) exchanger (NCX) play crucial roles in regulating [Ca(2+)](i) and both are dysfunctional during I/R, we tested the hypothesis that IHA hypoxia may prevent I/R-induced Ca(2+) overload by maintaining Ca(2+) homeostasis via SR and NCX mechanisms. We thus determined the dynamics of Ca(2+) transients and cell shortening during preischemia and I/R injury in ventricular cardiomyocytes from normoxic and IHA hypoxic rats. IHA hypoxia did not affect the preischemic dynamics of Ca(2+) transients and cell shortening, but it significantly suppressed the I/R-induced increase in resting [Ca(2+)](i) levels and attenuated the depression of the Ca(2+) transients and cell shortening during reperfusion. Moreover, IHA hypoxia significantly attenuated I/R-induced depression of the protein contents of SR Ca(2+) release channels and/or ryanodine receptors (RyRs) and SR Ca(2+) pump ATPase (SERCA2) and SR Ca(2+) release and uptake. In addition, a delayed decay rate time constant of Ca(2+) transients and cell shortening of Ca(2+) transients observed during ischemia was accompanied by markedly inhibited NCX currents, which were prevented by IHA hypoxia. These findings indicate that IHA hypoxia may preserve Ca(2+) homeostasis and contraction by preserving RyRs and SERCA2 proteins as well as NCX activity during I/R.

Altitude↗