To investigate the relationship between intracellular free Ca~ 2+ concentration (Ca~ 2+_i) and calcium-activated chloride (Cl_ca ) channels of pulmonary artery smooth muscle cells (PASMCs) in rats under acute and chro...To investigate the relationship between intracellular free Ca~ 2+ concentration (Ca~ 2+_i) and calcium-activated chloride (Cl_ca ) 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 Cl_ ca channels on PASMCs proliferation was assessed by MTT assay. The Cl_ ca 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+ _i was (123.63±18.98) nmol/L, and in hypoxic condition, Ca~ 2+ _i was (281.75±16.48) nmol/L (P<0.01). Under normoxic condition, Ca~ 2+ _i showed no significant change and no effect on Cl_ ca channels was observed (P>0.05). Chronic hypoxia increased Ca~ 2+ _i which opened Cl_ ca channels. The NFA and IAA-94 blocked the channels and decreased Ca~ 2+ _i from (281.75±16.48) nmol/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_ ca channels and had a positive-feedback in Ca~ 2+ _i. This may play an important role in hypoxic pulmonary hypertension. Under chronic hypoxic condition, Cl_ca channel may play a part in the regulation of proliferation of PASMCs.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 Ca2+ homeostasis.However,it r...Studies have suggested that aluminum,a neurotoxic metal,is involved in the progression of neurodegenerative diseases.Previous studies have confirmed that aluminum influences intracellular Ca2+ homeostasis.However,it remains unclear whether aluminum increases or decreases intracellular Ca2+ concentrations.The present study demonstrated that Al3+ competitively binds to calmodulin(CaM),together with Ca2+,which resulted in loss of capacity of CaM to bind to Ca2+,leading to increased [Ca2+]i.Al3+ stimulated voltage-gated calcium channels on cell membranes,which allowed a small quantity of Ca2+ into the cells.Al3+ also promoted calcium release from organelles by stimulating L-Ca2+ α1c to trigger calcium-induced calcium release.Although Al3+ upregulated expression of Na+/Ca2+ exchanger mRNA,increased levels of Ca2+ and Na+/Ca2+ exchanger did not maintain a normal Ca2+ balance.Al3+ resulted in disordered intracellular calcium homeostasis by affecting calcium channels,calcium buffering,and calcium expulsion.展开更多
文摘To investigate the relationship between intracellular free Ca~ 2+ concentration (Ca~ 2+_i) and calcium-activated chloride (Cl_ca ) 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 Cl_ ca channels on PASMCs proliferation was assessed by MTT assay. The Cl_ ca 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+ _i was (123.63±18.98) nmol/L, and in hypoxic condition, Ca~ 2+ _i was (281.75±16.48) nmol/L (P<0.01). Under normoxic condition, Ca~ 2+ _i showed no significant change and no effect on Cl_ ca channels was observed (P>0.05). Chronic hypoxia increased Ca~ 2+ _i which opened Cl_ ca channels. The NFA and IAA-94 blocked the channels and decreased Ca~ 2+ _i from (281.75±16.48) nmol/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_ ca channels and had a positive-feedback in Ca~ 2+ _i. This may play an important role in hypoxic pulmonary hypertension. Under chronic hypoxic condition, Cl_ca channel may play a part in the regulation of proliferation of PASMCs.
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 Ca2+ homeostasis.However,it remains unclear whether aluminum increases or decreases intracellular Ca2+ concentrations.The present study demonstrated that Al3+ competitively binds to calmodulin(CaM),together with Ca2+,which resulted in loss of capacity of CaM to bind to Ca2+,leading to increased [Ca2+]i.Al3+ stimulated voltage-gated calcium channels on cell membranes,which allowed a small quantity of Ca2+ into the cells.Al3+ also promoted calcium release from organelles by stimulating L-Ca2+ α1c to trigger calcium-induced calcium release.Although Al3+ upregulated expression of Na+/Ca2+ exchanger mRNA,increased levels of Ca2+ and Na+/Ca2+ exchanger did not maintain a normal Ca2+ balance.Al3+ resulted in disordered intracellular calcium homeostasis by affecting calcium channels,calcium buffering,and calcium expulsion.