To investigate the relationship between intracellular free Ca^2+ concentration ([Ca^2+ ]i ) and calcium-activated chloride (Clca) channels of pulmonary artery smooth muscle cells (PASMCs) in rats under acute a...To investigate the relationship between intracellular free Ca^2+ concentration ([Ca^2+ ]i ) and calcium-activated chloride (Clca) channels of pulmonary artery smooth muscle cells (PASMCs) in rats under acute and chronic hypoxic conditions, acute hypoxia-induced contraction was observed in rat pulmonary artery by using routine blood vascular perfusion in vitro. The fluorescence Ca^2+ indicator Fura-2/AM was used to observe [Ca^2+ ]i of rat PASMCs under normal and chronic hypoxic condition. The effect of Clca channels on PASMCs proliferation was assessed by MTT assay. The Clca channel blockers niflumic acid (NFA) and indaryloxyacetic acid (IAA-94) exerted inhibitory effects on acute hypoxia-evoked contractions in the pulmonary artery. Under chronic hypoxic condition, [Ca^2+ ]i was increased. Under normoxic condition, [Ca^2+ If was (123.634-18.98) nmol/ L, and in hypoxic condition, [Ca^2+]i wag (281. 754-16.48) nmol/L (P〈0. 01). Under normoxic condition, [Ca^2+ ]i showed no significant change and no effect on Clca channels was observed (P〉 0. 05). Chronic hypoxia increased [Ca^2+ ]i which opened Clca channels. The NFA and IAA-94 blocked the channels and decreased [Ca^2+ ]i from (281.75± 16.48) nmot/L to (117.66 ±15.36) nmol/L (P〈0.01). MTT assay showed that under chronic hypoxic condition NFA and IAA-94 decreased the value of absorbency (A value) from 0. 459±0. 058 to 0. 224±0. 025 (P〈0. 01). Hypoxia increased [Ca^2+ ]i which opened Cl~ channels and had a positive-feedback in [Ca^2+ ]i. This may play an important role in hypoxic pulmonary hypertension. Under chronic hypoxic condition, Clca channel may play a part in the regulation of proliferation of PASMCs.展开更多
The bark of Pteroce/tis tatarinowii is a raw material for manufacturing XuanPaper. The effects of Ca^(2+) concentrations on the accumulation of mineral elements in the bark,leaf and root of Pteroceltis tatarinowii wer...The bark of Pteroce/tis tatarinowii is a raw material for manufacturing XuanPaper. The effects of Ca^(2+) concentrations on the accumulation of mineral elements in the bark,leaf and root of Pteroceltis tatarinowii were studied under controlled conditions. The types ofHoagland nutrient solution with three Ca^(2+) concentrations levels (200, 400 and 600 μg·g^(-1))and a control (without Ca^(2+)) were designed to culture Pteroceltis tatarinowii. After 6 months,contents of seven mineral elements including Ca, K, Mg, Mn, Zn, Cu and Na in the root, leaf and barkwere analyzed. The results indicated that Ca accumulations content in the root, leaf and bark hadpositively relation with Ca^(2+) concentrations (200, 400, 600 μg · g^(-1)), and the order of theCa content in the three components was root>leaf>bark. Ca content in the root treated with 600 μg·g^(-1) Ca^(2+) concentrations was 5.5 times as high as that of the control, and about 1.4 times ashigh as that of the root treated in 200 and 400 μg/g Ca^(2+) concentrations respectively. On thecontrary, K and Mg contents in the root, leaf and bark were negatively related to Ca^(2+)concentrations, especially in the bark, and their accumulation trend followed the order ofleaf>root>bark. K content in the bark treated with 600 μg ·g^(-1) Ca^(2+) concentrations was 39.3%of that of the control, and was 79.0% and 91.8% of that of the bark treated with 200 μg ·g^(-1)and 400 μg ·g^(-1) Ca^(2+) concentrations respectively; Mg content in the bark treated with 600μg ·g^(-1) Ca^(2+) concentrations was 23.4% of that of the control, and was 27.1% and 35.4% ofthat of the bark treated with 200 and 400 μg·g^(-1) Ca^(2+) concentrations respectively. Comparedwith the control, the general tendency of Mn, Zn and Cu content decreased with increasing of Ca^(2+)concentrations and their contents were in the order: root>leaf>bark. Based on the results of thisstudy, the experiment has been useful for providing academic bases in improving the bark quality ofPteroceltis tatarinowii on non-limestone soil.展开更多
Studies have suggested that aluminum, a neurotoxic metal, is involved in the progression of neurodegenerative diseases. Previous studies have confirmed that aluminum influences intracellular Ca^2+ homeostasis. Howeve...Studies have suggested that aluminum, a neurotoxic metal, is involved in the progression of neurodegenerative diseases. Previous studies have confirmed that aluminum influences intracellular Ca^2+ homeostasis. However, it remains unclear whether aluminum increases or decreases intracellular Ca^2+ concentrations. The present study demonstrated that Al^3+ competitively binds to calmodulin (CAM), together with Ca^2+, which resulted in loss of capacity of CaM to bind to Ca^2+, leading to increased [Ca^2+]i. Al^3+ stimulated voltage-gated calcium channels on cell membranes, which allowed a small quantity of Ca^2+ into the cells. Al^3+ also promoted calcium release from organelles by stimulating L-Ca^2+αlc to trigger calcium-induced calcium release. Although Al^3+ upregulated expression of Na+/Ca^2+exchanger mRNA, increased levels of Ca^2+ and Na+/Ca^2+ exchanger did not maintain a normal Ca^2+ balance. Al^3+ resulted in disordered intracellular calcium homeostasis by affecting calcium channels, calcium buffering, and calcium expulsion.展开更多
BACKGROUND: Previous studies have demonstrated that intracellular Ca^2+ ([Ca^2+]) overload, excitotoxicity, free radical injury, and nitric oxide toxicity are involved in mechanisms of neuronal death in the ische...BACKGROUND: Previous studies have demonstrated that intracellular Ca^2+ ([Ca^2+]) overload, excitotoxicity, free radical injury, and nitric oxide toxicity are involved in mechanisms of neuronal death in the ischemic brain. OBJECTIVE: To investigate the influence of Panax quinquefo/ium saponins (PQS) on multiple factors-induced Ca^2+ overload in the rat pheochromocytoma (PC12) cell line. DESIGN, TIME AND SETTING: Intergroup comparison, in vitro study. The experiment was performed at the Heilongjiang Key Laboratory of Anti-fibrosis Biotherapy, Mudanjiang Medical University between November 2007 and April 2008. MATERIALS- In vitro cultured PC12 cells in the logarithmic phase were assigned into blank control, model, and drug treatment groups (10 μmol/L nimodipine; 40 μg/L, 100 μg/L, and 250 μg/L PQS). Nimodipine was purchased from Jiangsu Yangtze River Pharmacy Group Co., China; PQS (purity 〉 95%, HLPC grade) was provided by School of Basic Medical Sciences, Jilin University. Caffeine, Na2S2O4, L-glutamic acid (Glu), Fura-2/AM, and calcium ionophore A23187 were purchased from Sigma, USA. METHODS: PC12 cells in the model and drug treatment groups were separately incubated in glucose-free Hank's buffered saline solution + Na2S2O4 (2 mmol/L) for 6 hours, Glu (200 μmot/L) plus A23187 (0.05 μmol/L) for 6 hours, KCI (50 mmol/L) for 1 hour, and caffeine (5 mmol/L) for 3 hours to establish models of intracellular Ca^2+ overload induced by oxygen and glucose deprivation, Glu, A23187, high K+, or caffeine. In addition, control cells were incubated in high-glucose DMEM culture medium. MAIN OUTCOME MEASURES: [Ca^2+]i changes in PC12 cells exposed to oxygen-glucose deprivation, Glu, A23187, high K^+, or caffeine were detected using spectrofluorometer. RESULTS: PQS blocked the [Ca^2+]i increase induced by oxygen-glucose deprivation, Glu, A23187, high K+, or caffeine. In particular, high-dose PQS was most effective (P 〈 0.01). PQS significantly inhibited Glu- or caffeine-induced [Ca^2+]i increases in the absence of extracellular Ca^2+, but nimodipine did not. CONCLUSION: PQS blocked intracellular Ca^2+ overload induced by oxygen-glucose deprivation, Glu, A23187, high K^+, or caffeine. This mechanism might be involved in the attenuation of neuronal apoptosis following ischemic brain injury.展开更多
The effect of Ca^2+ on CO2 corrosion to X65 pipeline steel was investigated in the simulated stratum water of an oil field containing different concentrations of Ca^2+. It is found that Ca^2+ can enhance the corros...The effect of Ca^2+ on CO2 corrosion to X65 pipeline steel was investigated in the simulated stratum water of an oil field containing different concentrations of Ca^2+. It is found that Ca^2+ can enhance the corrosion rate, especially in the Ca^2+ concentration from 256 to 512 mg/L, which can be attributed to the growing grain size and loosing structure of corrosion scales with increasing Ca^2+ concentration. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) investigations reveal that a complex carbonate (Fe, Ca)CO3 forms at high Ca^2+ concentration due to the gradual replacement of Fe^2+ in FeCO3 by Ca^2+.展开更多
WT5”BZ] To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation. [WT5”BX]Methods.[WT5”BZ] Thymocytes from Kunming mice exposed to whole body irradiation(WBI) with ...WT5”BZ] To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation. [WT5”BX]Methods.[WT5”BZ] Thymocytes from Kunming mice exposed to whole body irradiation(WBI) with different doses of X rays were analyzed for the changes in signal molecules of the phospholipase C phosphatidylinositol biphosphate(PLC IP2) and G protein adenylate cyclase(AC) pathways. [WT5”BX]Results.[WT5”BZ]It was found that[Ca 2+ ] i increased in response to doses within 0 2 Gy which was most marked after 0 075 Gy and the increase was accentuated in the presence of Con A. The changes in CD3 and calcineurin(CN) expression of the thymocytes followed the same pattern as the alterations in [Ca 2+ ] i after LDR. The expression of α,β1 and β2 isoforms of protein kinase C(PKC) was all up regulated after 0 075 Gy with the increase in PKC β1 expression being most marked. The cAMP/cGMP ratio and PKA activity of the thymocytes was lowered after low dose radiation and increased after doses above 0 5 Gy in a dose dependent manner, thus giving rise to J shaped dose response curves. The Ca antagonist TMB 8 and cAMP stimulant cholera toxin suppressed the augmented thymocyte proliferation induced by LDR. [WT5”BX]Conclusion.[WT5”BZ]Data presented in the present paper suggest that activation of the PLC PIP2 signal pathway and suppression of the AC cAMP signal pathway are involved in the stimulation of the thymocytes following WBI with low dose X rays.展开更多
文摘To investigate the relationship between intracellular free Ca^2+ concentration ([Ca^2+ ]i ) and calcium-activated chloride (Clca) channels of pulmonary artery smooth muscle cells (PASMCs) in rats under acute and chronic hypoxic conditions, acute hypoxia-induced contraction was observed in rat pulmonary artery by using routine blood vascular perfusion in vitro. The fluorescence Ca^2+ indicator Fura-2/AM was used to observe [Ca^2+ ]i of rat PASMCs under normal and chronic hypoxic condition. The effect of Clca channels on PASMCs proliferation was assessed by MTT assay. The Clca channel blockers niflumic acid (NFA) and indaryloxyacetic acid (IAA-94) exerted inhibitory effects on acute hypoxia-evoked contractions in the pulmonary artery. Under chronic hypoxic condition, [Ca^2+ ]i was increased. Under normoxic condition, [Ca^2+ If was (123.634-18.98) nmol/ L, and in hypoxic condition, [Ca^2+]i wag (281. 754-16.48) nmol/L (P〈0. 01). Under normoxic condition, [Ca^2+ ]i showed no significant change and no effect on Clca channels was observed (P〉 0. 05). Chronic hypoxia increased [Ca^2+ ]i which opened Clca channels. The NFA and IAA-94 blocked the channels and decreased [Ca^2+ ]i from (281.75± 16.48) nmot/L to (117.66 ±15.36) nmol/L (P〈0.01). MTT assay showed that under chronic hypoxic condition NFA and IAA-94 decreased the value of absorbency (A value) from 0. 459±0. 058 to 0. 224±0. 025 (P〈0. 01). Hypoxia increased [Ca^2+ ]i which opened Cl~ channels and had a positive-feedback in [Ca^2+ ]i. This may play an important role in hypoxic pulmonary hypertension. Under chronic hypoxic condition, Clca channel may play a part in the regulation of proliferation of PASMCs.
基金This paper is supported by National Natural Science Foundation of China (No. 39970608).
文摘The bark of Pteroce/tis tatarinowii is a raw material for manufacturing XuanPaper. The effects of Ca^(2+) concentrations on the accumulation of mineral elements in the bark,leaf and root of Pteroceltis tatarinowii were studied under controlled conditions. The types ofHoagland nutrient solution with three Ca^(2+) concentrations levels (200, 400 and 600 μg·g^(-1))and a control (without Ca^(2+)) were designed to culture Pteroceltis tatarinowii. After 6 months,contents of seven mineral elements including Ca, K, Mg, Mn, Zn, Cu and Na in the root, leaf and barkwere analyzed. The results indicated that Ca accumulations content in the root, leaf and bark hadpositively relation with Ca^(2+) concentrations (200, 400, 600 μg · g^(-1)), and the order of theCa content in the three components was root>leaf>bark. Ca content in the root treated with 600 μg·g^(-1) Ca^(2+) concentrations was 5.5 times as high as that of the control, and about 1.4 times ashigh as that of the root treated in 200 and 400 μg/g Ca^(2+) concentrations respectively. On thecontrary, K and Mg contents in the root, leaf and bark were negatively related to Ca^(2+)concentrations, especially in the bark, and their accumulation trend followed the order ofleaf>root>bark. K content in the bark treated with 600 μg ·g^(-1) Ca^(2+) concentrations was 39.3%of that of the control, and was 79.0% and 91.8% of that of the bark treated with 200 μg ·g^(-1)and 400 μg ·g^(-1) Ca^(2+) concentrations respectively; Mg content in the bark treated with 600μg ·g^(-1) Ca^(2+) concentrations was 23.4% of that of the control, and was 27.1% and 35.4% ofthat of the bark treated with 200 and 400 μg·g^(-1) Ca^(2+) concentrations respectively. Comparedwith the control, the general tendency of Mn, Zn and Cu content decreased with increasing of Ca^(2+)concentrations and their contents were in the order: root>leaf>bark. Based on the results of thisstudy, the experiment has been useful for providing academic bases in improving the bark quality ofPteroceltis tatarinowii on non-limestone soil.
基金supported by the Department of Hygienic Toxicology,Public Health College,Harbin Medical University,China
文摘Studies have suggested that aluminum, a neurotoxic metal, is involved in the progression of neurodegenerative diseases. Previous studies have confirmed that aluminum influences intracellular Ca^2+ homeostasis. However, it remains unclear whether aluminum increases or decreases intracellular Ca^2+ concentrations. The present study demonstrated that Al^3+ competitively binds to calmodulin (CAM), together with Ca^2+, which resulted in loss of capacity of CaM to bind to Ca^2+, leading to increased [Ca^2+]i. Al^3+ stimulated voltage-gated calcium channels on cell membranes, which allowed a small quantity of Ca^2+ into the cells. Al^3+ also promoted calcium release from organelles by stimulating L-Ca^2+αlc to trigger calcium-induced calcium release. Although Al^3+ upregulated expression of Na+/Ca^2+exchanger mRNA, increased levels of Ca^2+ and Na+/Ca^2+ exchanger did not maintain a normal Ca^2+ balance. Al^3+ resulted in disordered intracellular calcium homeostasis by affecting calcium channels, calcium buffering, and calcium expulsion.
基金Supported by:the Natural Science Foundation of Heilongjiang Province,No ZA2006-07
文摘BACKGROUND: Previous studies have demonstrated that intracellular Ca^2+ ([Ca^2+]) overload, excitotoxicity, free radical injury, and nitric oxide toxicity are involved in mechanisms of neuronal death in the ischemic brain. OBJECTIVE: To investigate the influence of Panax quinquefo/ium saponins (PQS) on multiple factors-induced Ca^2+ overload in the rat pheochromocytoma (PC12) cell line. DESIGN, TIME AND SETTING: Intergroup comparison, in vitro study. The experiment was performed at the Heilongjiang Key Laboratory of Anti-fibrosis Biotherapy, Mudanjiang Medical University between November 2007 and April 2008. MATERIALS- In vitro cultured PC12 cells in the logarithmic phase were assigned into blank control, model, and drug treatment groups (10 μmol/L nimodipine; 40 μg/L, 100 μg/L, and 250 μg/L PQS). Nimodipine was purchased from Jiangsu Yangtze River Pharmacy Group Co., China; PQS (purity 〉 95%, HLPC grade) was provided by School of Basic Medical Sciences, Jilin University. Caffeine, Na2S2O4, L-glutamic acid (Glu), Fura-2/AM, and calcium ionophore A23187 were purchased from Sigma, USA. METHODS: PC12 cells in the model and drug treatment groups were separately incubated in glucose-free Hank's buffered saline solution + Na2S2O4 (2 mmol/L) for 6 hours, Glu (200 μmot/L) plus A23187 (0.05 μmol/L) for 6 hours, KCI (50 mmol/L) for 1 hour, and caffeine (5 mmol/L) for 3 hours to establish models of intracellular Ca^2+ overload induced by oxygen and glucose deprivation, Glu, A23187, high K+, or caffeine. In addition, control cells were incubated in high-glucose DMEM culture medium. MAIN OUTCOME MEASURES: [Ca^2+]i changes in PC12 cells exposed to oxygen-glucose deprivation, Glu, A23187, high K^+, or caffeine were detected using spectrofluorometer. RESULTS: PQS blocked the [Ca^2+]i increase induced by oxygen-glucose deprivation, Glu, A23187, high K+, or caffeine. In particular, high-dose PQS was most effective (P 〈 0.01). PQS significantly inhibited Glu- or caffeine-induced [Ca^2+]i increases in the absence of extracellular Ca^2+, but nimodipine did not. CONCLUSION: PQS blocked intracellular Ca^2+ overload induced by oxygen-glucose deprivation, Glu, A23187, high K^+, or caffeine. This mechanism might be involved in the attenuation of neuronal apoptosis following ischemic brain injury.
基金supported by the National Natural Science Foundation of China (No.50571012)
文摘The effect of Ca^2+ on CO2 corrosion to X65 pipeline steel was investigated in the simulated stratum water of an oil field containing different concentrations of Ca^2+. It is found that Ca^2+ can enhance the corrosion rate, especially in the Ca^2+ concentration from 256 to 512 mg/L, which can be attributed to the growing grain size and loosing structure of corrosion scales with increasing Ca^2+ concentration. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) investigations reveal that a complex carbonate (Fe, Ca)CO3 forms at high Ca^2+ concentration due to the gradual replacement of Fe^2+ in FeCO3 by Ca^2+.
基金This work was supported by a grant from NSFC (No.39570188)
文摘WT5”BZ] To study the molecular mechanism of the stimulatory effect of low dose radiation(LDR) on T cell activation. [WT5”BX]Methods.[WT5”BZ] Thymocytes from Kunming mice exposed to whole body irradiation(WBI) with different doses of X rays were analyzed for the changes in signal molecules of the phospholipase C phosphatidylinositol biphosphate(PLC IP2) and G protein adenylate cyclase(AC) pathways. [WT5”BX]Results.[WT5”BZ]It was found that[Ca 2+ ] i increased in response to doses within 0 2 Gy which was most marked after 0 075 Gy and the increase was accentuated in the presence of Con A. The changes in CD3 and calcineurin(CN) expression of the thymocytes followed the same pattern as the alterations in [Ca 2+ ] i after LDR. The expression of α,β1 and β2 isoforms of protein kinase C(PKC) was all up regulated after 0 075 Gy with the increase in PKC β1 expression being most marked. The cAMP/cGMP ratio and PKA activity of the thymocytes was lowered after low dose radiation and increased after doses above 0 5 Gy in a dose dependent manner, thus giving rise to J shaped dose response curves. The Ca antagonist TMB 8 and cAMP stimulant cholera toxin suppressed the augmented thymocyte proliferation induced by LDR. [WT5”BX]Conclusion.[WT5”BZ]Data presented in the present paper suggest that activation of the PLC PIP2 signal pathway and suppression of the AC cAMP signal pathway are involved in the stimulation of the thymocytes following WBI with low dose X rays.