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Objective To investigate the effects of total alkaloids in Buxus microphylla leaves (ABML) on isolated rats thoracic aorta rings,and then to explore the possible mechanisms underlying the effects.MethodsThoracic aortas of Wistar rats were isolated,removed,and mounted onto an organ bath.The effects of ABML at different concentration on the contraction of isolated thoracic aorta rings (with and without endothelium) precontracted with KC1 or PE were observed with organ bath technique.Dose-effect curves of CaCl2 were recorded by organ bath technique.The concentration of intracellular Ca2+ ([Ca2+]i) increased by PE,KCI,and caffeine in the presence of ABML was determined using Ca2+ sensitive fluorescence indicator Fura-2/AM loaded thoracic aorta vascular smooth muscle (VSM) cells of rats.ResultsIn aorta rings precontracted with PE and KCI,ABML produced concentrationdependent relaxation in both intact and denuded endothelium ring groups.There was no difference in the inhibition of contraction between the intact and denuded endothelium ring groups at the same concentration.Exposure of isolated thoracic aorta rings to ABML led to a significant reduction in the contracting response induced by CaCI2,and shifted the cumulative concentration-response curves to right.ABML could significantly inhibit the extracellular Ca2+ influx induced by PE and KCI under [Ca2+]0 of 1.5 mmol/L,with inhibitory ratios of 40.2％ and 49.9％,respectively.In the case of Ca2+-free,ABML could significantly inhibit the intracellular Ca2+ release induced by PE,with inhibitory ratio of 72.4％.ConclusionABML relaxes thoracic aorta VSM cells by suppressing influx of extracellular Ca2+ via voltage-dependent Ca2+ channel and receptor-operated Ca2+ channel.
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Objective To observe the effects of flunarizine on the intracerebral hemorrhage (ICH) of Wistar rats at different time points. Methods An ICH rat model was established by collagenase. The concentrations of intracellular free Ca 2+ at different time points after ICH were determined by the fluorescence detector with an indicator, Fura 2/AM. The effects of flunarizine on the concentrations at different time points were also observed. Results The concentration of intracellular free Ca 2+ began to increase at 0.5 h, increased significantly at 6 h, and peaked at 24 h (about 4 folds as high as that before hemorrhage), but began to decrease at 72 h after acute intracerebral hemorrhage. Flunarizine decreased the concentration of intracellular free Ca 2+ significantly ( P
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Objectives: To clarify the antiarrhythmia mechanism of matrine by observing its effects on intracellular calcium concentration in cultured myocardial cells of SD rats. Methods: Myocardial cells of newborn(sucking) rats were fed with culture medium supplemented with verapamil、 potassium chloride and different dose of matrine, respectively. By means of the image analysis system, intensity changes of intracellular calcium were determined with the fluorescent probe to estimate indirectly inward calcium influx under the influence of matrine. Results: It was found that high potassium caused an increase in fluorescent intensity of intracellular calcium which could be inhibited by matrine. Conclusion: It is suggested that matrine may be a kind of calcium antagonium producing its antiarrhythmic action.
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0 05), being ( 187 0?10 7) nmol/L in average. Moreo ver, it was not significantly different from the cells cultured at day 0, ei ther . However, [Ca 2+ ]i increased significantly(P
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Objective:To investigate the regulation of PTEN with RNAi on NR2B after OGD.Methods:In the OGD model with anaerobic gas mixture and deoxygenated,glucose-free extracellular solution,shRNAspten-GFP and unrelated control plasmid PshGFP transfection were done respectively.The quantities of NR2B in the neuronal membrane were quantitatively measured with colorimetric assay,and the expression of NR2B mRNA were analyzed by RT-PCR.The neuronal activity was analyzed by AlamarBlue andintracellular free calcium concentration were measured with Fura-2 AM by laser confocal microscope(LCM).Results:shRNAspten-GFP plasmid can been expressed successfully in cultured neurons.The study demonstrated that there are numerous NR2B subunit expression on neuronal membrane by colorimetric assay(OPD)assay and RT-PCR.The expression and quantity of neuronal NR2B with shRNAspten-GFP treatment was significantly decrease after oxygen and glucose deprivation(OGD)and reperfusion(P
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AIM To study the calcium antagonistic effects of Magnesium salicylate in central nervous system. MTEHODS Using calcium sensitive fluorescence indicator Fura-2 technique. RESULTS Resting [Ca 2+ ] i in brain cells under different extracellular calcium concentration(0,0 01,0 1,1 0,1 3 mmol?L -1 )were 41?5,59?6,84 7?2 5,104?7,(126?5)nmol?L -1 respectively( n =8～47).MgS 0 2 mmol?L -1 had no significant effects on resting [Ca 2+ ] i.At the same time, MgS (0 05～0 4 mmol?L -1 ) concentration dependently inhibited the [Ca 2+ ] i elevation induced by high extracellular potassium or L -glutamate in the presence of extracellular [Ca 2+ ] i 1 3 mmol?L -1 . The IC 50 values were 0 323 mmol?L -1 (95% CI 0 122～0 854 mmol?L -1 ) and 0 124 mmol?L -1 (95% CI 0 073～0 210 mmol?L -1 ) separately. CONCLUSION MgS possesses inhibitory effects on voltage-activated calcium channel and receptor-operated calcium chanel in CNS.
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The glutaramic acid derivative cholecystokinin ( CCK ) receptor antagonist, CR1409 was tested for its ability to inhibit CCK induced increase in cytosolic calcium concentration in isolated rat pancreatic acinar cells using fura-2 as calcium probe. Preaddition of 10?mol/L CR1409 completely inhibited the increase of cytosolic calcium concertration induced with 1 nmol/L CCK, but had no antagonistic effect on carbacholine bombesin-induced increase in cytosolic calcium concentration. The half maximal inhibition was obtained for 0.37?mol/L, corresponding to a potency a hundred fold higher than that of db cGMP. In the presence of increasing concentrations of CR1409, the response curves of CCK concentrations were shifted to the right but the same maximum was achieved. Schild representation gave a straight line with a slope close to one ( n = 0.92 ) and pA2 value of 6.93. These findings therefore support that CR1409 is a powerful competitive and specific antagonist bf CCK-induced increase in cytosolic calcium Concentration in isolated rat pancreatic acinar cells and provide further evidence for the role of this ion as an intracellular mediator of pancreatic CCK receptor.