EFFECTS OF PDGF-BB ON INTRACELLULAR CALCIUM CONCENTRATION AND PROLIFERATION IN CULTURED GLOMERULAR MESANGIAL CELLS

Objective To investigate the relationship between the alteration of intracellular calcium concentration and proliferation in cultured glomerular mesangial cells. Methods Rat mesangial cells were cultured. lntracellular calcium concentrations were measured by confocal Laser Scanning Microscopy and Fura-3 fluorescence dyeing techniques. Cell growth was measured by MTT assay. Results PDGF-BB increased intracellular calcium concentrations in a dose-dependent manner, and at the same time promote the proliferation of mesangial cells. After preincubation with calcium channel blocker nifedipine or angiotensin converting enzyme inhibitor captopril, both the increase of intracellular calcium concentrations and cell proliferations induced by PDGF-BB were inhibited. Tripteriglum Wilfordii Glycosides （TMG） significantly inhibited the mesangial cell proliferations, but it had no significant effect on intracellular calcium concentrations. Conclusion There was a positive relationship between the elevation of intracellular calcium concentration and cell proliferation in glomerular mesangial cells, but the increase of intracellular calcium concentrations wasn＇t the only way for proliferation.

Distribution of Terbium and Increase of Calcium Concentration in the Organs of Mice iv-Administered With Terbium Chloride

To investigate the biobeical effects of terbium (Tb), male mice were intravenously ad ministered with TbCl3 at 10, 25, or 50 mg Tb/kg. Time-course and dose-related changes in organ distributions of Tb were determined . More than 95 % of the Tb in blood was in plas ma, and the concentrations decreased rapidly. Contrary to normal pharmacokinetics, Tb con centrations in plasma were higher in the 10 mg/kg group than in the 50 mg/kg group. The concentrations after injection of 25 mg/kg were between 10 and 50 mg/kg injections. Tb was incorporated mainly in liver, lung, and spleen. In all groups more than 80% of Tb adminis tered were found in these three organs. Disappearance of Tb in these organs was very slow.Tb was also found in kidney, heart and other organs. Coincidentally, it was found that the Ca concentration was increased in organs in which Tb was incorporated. After administration of Tb (50 mg/kg) the Ca concentration, compared to the controls, was 70-fold in spleen, 20-fold in lung, and 6-fold in liver. There were highly positive correlations between Tb and Ca concentrations in organs. Excretion of Tb in urine was 0. 15 ～ 0. 3 % and that in feces was 1.7～12. 5 % for up to 7 days. These results indicate that liver, lung, and spleen are the main target organs of Tb administered intravenously, and that the increase in Ca concentrations is one of the important biological effects of Tb in target organs

Model for Influences of Magnetic Fields on Intracellular Calcium Oscillations

Based on the model of the two calcium stores developed by Goldbeter, the influence of external magnetic field on the calcium concentration has been discussed. We believe that the cell membrane is a major site of interaction for extremely-low-frequency （ELF） electromagnetic fields, and the permeability of ions can be changed with the changing electromagnetic fields. It is shown that magnetic field initiates intraeellular calcium oscillation with a threshold in flux density, and that the calcium oscillations do not occur if the density of magnetic field is below the threshold. The results of theoretical calculation are consistent with that of the experiment. The intracellular free calcium concentrations of different cells exposed to the same magnetic fields are different from each other. It is indicated that the different behaviors such as oscillation, rise and invariability of calcium concentration are associated with the sort of cells.

Effects of Iptakalim on intracellular free calcium concentration of cultured rabbit pulmonary arterial smooth muscle cells

Objective：To explore the effects of Iptakalim on intracellular free calcium concentration and on the proliferation of cultured rabbit pulmonary arterial smooth muscle cells induced by endothelin-1 （ET-1） in vitro. Methods：A cell culture model, [^3H]-thymidine（[^3H]-TdR） incorporation test and confocal microscope were used to observe proliferation and intracellular free calcium concentration（[Ca^2±]） of rabbit PASMC induced by ET-1 in vitro. Results：The value of [^3H]-TdR incorporation in ET-1 group was increased 1.468 times higher than that in control group. Iptakalim at the concentration of 10^-7mol/L, 10^-6mol/L ,10^-5 mol/L lowered [^3H]-TdR incorporation by （19.8 ± 4.6）%, （41.2 ± 9.5）%, （54.7 ± 10.1）%, respectively, compared with the value of the cells treated with ET-1（P〈 0.01）; The intracellular fluorescence intensity of PASMC in ET-1 group was increased from 73.70 ± 10.12 to 143.84 ± 28.23, significantly higher than that in control group（P 〈 0.01）; whereas with Iptakalim,the fluorescence intensity（FI） was only increased from 74.30 ± 10.20 to 86.03 ± 9.82, significantly lower than that in ET-1 group（P 〈 0.01）. Conclusion：Iptakalim inhibited proliferation of PASMC and decreased intracellular free calcium concentration of cultured rabbit PASMC induced by ET-1.

A viral vector expressing hypoxia-inducible factor 1 alpha inhibits hippocampal neuronal apoptosis

Hypoxia-inducible factor 1 （HIF-1） attenuates amyloid-beta protein neurotoxicity and decreases apoptosis induced by oxidative stress or hypoxia in cortical neurons. In this study, we construct-ed a recombinant adeno-associated virus （rAAV） vector expressing the human HIF-1αgene （rAAV-HIF-1α）, and tested the assumption that rAAV-HIF-1αrepresses hippocampal neuronal apoptosis induced by amyloid-beta protein. Our results conifrmed that rAAV-HIF-1αsigniifcant-ly reduces apoptosis induced by amyloid-beta protein in primary cultured hippocampal neurons. Direct intracerebral rAAV-HIF-1αadministration also induced robust and prolonged HIF-1αproduction in rat hippocampus. Single rAAV-HIF-1αadministration resulted in decreased apoptosis of hippocampal neurons in an Alzheimer＇s disease rat model established by intrace-rebroventricular injection of aggregated amyloid-beta protein （25-35）. Our in vitro and in vivo ifndings demonstrate that HIF-1 has potential for attenuating hippocampal neuronal apoptosis induced by amyloid-beta protein, and provides experimental support for treatment of neurode-generative diseases using gene therapy.

Contractility detection of isolated mouse papillary muscle using myotronic Myostation-Intact device

Background:To understand the relationship between myocardial contractility and ex-ternal stimuli,detecting ex vivo myocardial contractility is necessary.Methods:We elaborated a method for contractility detection of isolated C57 mouse papillary muscle using Myostation-Intact system under different frequencies,volt-ages,and calcium concentrations.Results:The results indicated that the basal contractility of the papillary muscle was 0.27±0.03 mN at 10 V,500-ms pulse duration,and 1 Hz.From 0.1 to 1.0 Hz,con-tractility decreased with an increase in frequency(0.45±0.11-0.10±0.02 mN).The voltage-initiated muscle contractility varied from 3 to 6 V,and the contractility gradu-ally increased as the voltage increased from 6 to 10 V(0.14±0.02-0.28±0.03 mN).Moreover,the muscle contractility increased when the calcium concentration was increased from 1.5 to 3 mM(0.45±0.17-1.11±0.05 mN);however,the contractility stopped increasing even when the concentration was increased to 7.5 mM(1.02±0.23 mN).Conclusions:Our method guaranteed the survivability of papillary muscle ex vivo and provided instructions for Myostation-Intact users for isolated muscle contractility investigations.

Effect of 935-MHz Phone-simulating Electromagnetic Radiation on Endometrial Glandular Cells during Mouse Embryo Implantation

This study examined the impact of 935MHz phone-simulating electromagnetic radiation on embryo implantation of pregnant mice.Each 7-week-old Kunming (KM) female white mouse was set up with a KM male mouse in a single cage for mating overnight after induction of ovulation.In the first three days of pregnancy,the pregnant mice was exposed to electromagnetic radiation at low-intensity (150 μW/cm2,ranging from 130 to 200 μW/cm2,for 2-or 4-h exposure every day),mid-intensity (570 μW/cm2,ranging from 400 to 700 μW/cm2,for 2-or 4-h exposure every day) or high-intensity (1400 μW/cm2,ranging from 1200 to 1500 μW/cm2,for 2-or 4-h exposure every day),respectively.On the day 4 after gestation (known as the window of murine embryo implantation),the endometrium was collected and the suspension of endometrial glandular cells was made.Laser scanning microscopy was employed to detect the mitochondrial membrane potential and intracellular calcium ion concentration.In high-intensity,2-and 4-h groups,mitochondrial membrane potential of endometrial glandular cells was significantly lower than that in the normal control group (P<0.05).The calcium ion concentration was increased in low-intensity 2-h group but decreased in high-intensity 4-h group as compared with the normal control group (P<0.05).However,no significant difference was found in mitochondrial membrane potential of endometrial glandular cells between low-or mid-intensity groups and the normal control group,indicating stronger intensity of the electromagnetic radiation and longer length of the radiation are required to inflict a remarkable functional and structural damage to mitochondrial membrane.Our data demonstrated that electromagnetic radiation with a 935-MHz phone for 4 h conspicuously decreased mitochondrial membrane potential and lowered the calcium ion concentration of endometrial glandular cells.It is suggested that high-intensity electromagnetic radiation is very likely to induce the death of embryonic cells and decrease the chance of their implantation,thereby posing a high risk to pregnancy.

Arginine promotes myogenic differentiation and myotube formation through the elevation of cytoplasmic calcium concentration

This study aimed to explore the mechanism underlying arginine-promoted myogenesis of myoblasts.C2C12 cells were cultured with a medium containing 0.1,0.4,0.8,or 1.2 mmol/L arginine,respectively.Cell proliferation,viability,differentiation indexes,cytoplasmic Ca^(2+)concentration,and relative mRNA expression levels of myogenic regulatory factors(MRF)and key Ca2+channels were measured in the absence or presence of 2 chemical inhibitors,dantrolene(DAN,10μmol/L)and nisoldipine(NIS,10μmol/L),respectively.Results demonstrated that arginine promoted myogenic differentiation and myotube formation.Compared with the control(0.4 mmol/L arginine),1.2 mmol/L arginine upregulated the relative mRNA expression levels of myogenin(MyoG)and Myomaker at d 2 during myogenic induction(P<0.05).Cytoplasmic Ca^(2+)concentrations were significantly elevated by arginine supplementation at d 2 and 4(P<0.05).Relative mRNA expression levels of Ca^(2+)channels including the type 1 ryanodine recepto r(RyR1)and voltage-gated Ca^(2+)channel(Cav1.1)were upregulated by 1.2 mmol/L arginine during2-d myogenic induction(P<0.01).However,arginine-promoted myogenic potential of myoblasts was remarkably compromised by DAN and NIS,respectively(P<0.05).These findings evidenced that the supplementation of arginine promoted myogenic differentiation and myotube formation through increasing cytoplasmic Ca^(2+)concentration from both extracellular and sarcoplasmic reticulum Ca^(2+).

Effect of combining different calcium concentration dialysate on calcium balance in peritoneal dialysis patients

Background Calcium and phosphorus metabolic disturbance are common in dialysis patients and associated with increased morbidity and mortality. Therefore, maintaining the balance of calcium and phosphate metabolism and suitable intact parathyroid hormone （iPTH） level has become the focus of attention. We investigated the effects of different peritoneal dialysate calcium concentrations on calcium phosphate metabolism and iPTH in continuous ambulatory peritoneal dialysis （CAPD） patients. Methods Forty stable CAPD patients with normal serum calcium were followed for six months of treatment with 1.25 mmol/L calcium dialysate （DCa1.25, PD4, 22 patients） or a combination of 1.75 mmol/L calcium dialysate （DCa1.75, PD2） and PD4 （18 patients） twice a day respectively. Total serum calcium （after albumin correction）, serum phosphorus, iPTH, alkaline phosphatase （ALP） and blood pressure were recorded before and 1, 3 and 6 months after treatment commenced. Results No significant difference was found in baseline serum calcium, phosphorus between the two patient groups, but the levels of iPTH were significantly different. No significant changes were found in the dosage of calcium carbonate and active vitamin D during 6 months. In the PD4 group, serum calcium level at the 1st, 3rd, 6th months were significantly lower than the baseline （P 〈0.05）. There was no significant difference in serum phosphorus after 6 months treatment. iPTH was significantly higher （P 〈0.001） at the 1st, 3rd, and 6th months compared with the baseline. No differences were seen in ALP and blood pressure. In the PD4＋PD2 group, no significant changes in serum calcium, phosphorus, iPTH, ALP and BP during the 6-month follow-up period. Conclusions Treatment with 1.25 mmol/L calcium dialysate for six months can decrease serum calcium, increase iPTH, without change in serum phosphorus, ALP, and BP. The combining of PD4 and PD2 can stabilize the serum calcium and avoid fluctuations in iPTH levels.

Changes of neuronal calcium channel following brain damage induced by injection of pertussis bacilli in rats

Objective: To explore changes of neuronal calcium channel following brain damage induced by injection of pertussis bacilli in rats, and to investigate the relationship between cytosolic free calcium concentration ([Ca 2+ ] i) in the synaptosome and Ca 2+ ATPase activities of mitochondria. Methods: The level of [Ca 2+ ] i in the synaptosome and Ca 2+ ATPase activities of mitochondria in the acute brain damage induced by injection of pertussis bacilli (PB) in rat was determined and nimodipine was administrated to show its effects on [Ca 2+ ] i in the synaptosome and on alteration of Ca 2+ ATPase activity in the mitochondria. Seventy three rats were randomly divided into four groups, ie, normal control group (Group A), sham operation control group (Group B), PB group (Group C) and nimodipine treatment group (Group D). Results: The level of [Ca 2+ ] i was significantly increased in the PB injected cerebral hemisphere in the Group C as compared with that in the Group A and the Group B at 30 minutes after injection of PB. The level of [Ca 2+ ] i was kept higher in the 4 hours and 24 hours subgroups after the injection in the Group C (P< 0.05 ). In contrast, the Ca 2+ ATPase activities were decreased remarkably among all of the subgroups in the Group C. Nimodipine, which was administered after injection of PB, could significantly decrease the [Ca 2+ ] i and increase the activity of Ca 2+ ATPase (P< 0.05 ). Conclusions: The neuronal calcium channel is opened after injection of PB. There is a negative correlation between activities of Ca 2+ ATPase and [Ca 2+ ] i. Nimodipine can reduce brain damage through stimulating the activities of Ca 2+ ATPase in the mitochondria, and decrease the level of [Ca 2+ ] i in the synaptosome. Treatment with nimodipine dramatically reduces the effects of brain damage induced by injection of PB.

Mechanisms of peroxynitrite-induced [Ca^(2+)]_i increase in single neuronal cell

The mechanism of peroxynitrite (ONOO -)induced [Ca 2+ ] i increase in single MN9D cell (Dopaminergic neuroblastoma cell line) was studied by using Fura2 microfluorometric technique. The results show that ONOO - caused a rapid increase of [Ca 2+ ] i when ONOO - was puffed to the cell. Removing Ca 2+ from the bath or using calcium channel antagonist (CdCl 2, Nifedipine) greatly inhibited the [Ca 2+ ] i increase induced by ONOO -, suggesting that the opening of LCa 2+ channel makes a great contribution to the [Ca 2+ ]\-i increase. The effect of sulfhydryl reductive agent (DTT) on ONOO -induced [Ca 2+ ]\-i increase suggests that ONOO -activating LCa 2+ channel is partly related to its oxidative speciality.