The aminoglycoside antibiotic gentamicin is able to alter metabolic activity and morphology of MDCK-C11 cells: a cell model of intercalated cells

It is well known that the aminoglycoside antibiotic gentamicin is capable of causing damage to kidney cells. Given the known involvement of Ca2+ in the nephrotoxic action of gentamicin, the purpose of this study was to establish a relationship between the concentration of intracellular Ca2+ ([Ca2+]i) and cellular cytotoxicity using MDCK-C11 cells, a clone that has several properties that resemble those of intercalated cells of the distal nephron. Changes in [Ca2+]i was determined using fluorescence microscopy. Cell viability was evaluated by the neutral red method, and cell cytotoxicity by the MTT method. The [Ca2+]i gradually increased when cells were exposed to 0.1 mM gentamicin for 10, 20, and 30 min. The presence of extracellular Ca2+ was found to be necessary to stimulate the increase in [Ca2+]i induced by gentamicin, since this stimulus disappeared by using 1.8 mM EGTA (a Ca2+ chelator). Morphological changes were observed with scanning electron microscopy in epithelial cells exposed to the antibiotic. Furthermore, with the MTT method, a decrease in metabolic activity induced by gentamicin was observed, which indicates a cytotoxic effect. In conclusion, gentamicin was able to alter [Ca2+]i, change the morphology of MDCK-C11 cells, and promote cytotoxicity.

Polysaccharides extracted from the roots of Bupleurum chinense DC modulates macrophage functions / 中国天然药物

The present study aimed to investigate the effects of polysaccharides extracted from Bupleurum chinense DC (BCPs) on macrophage functions. In the in vivo experiment, 1 mL of 5% sodium thioglycollate was injected into the abdomen of the mice on Day 0 and macrophages were harvested on Day 4. The macrophages were cultured in plates and treated with different concentrations of BCPs and stimulus. Effects of BCPs on macrophage functions were assessed by chemotaxis assay, phagocytosis assay and Enzyme-Linked Immunosorbent Assay (ELISA). Our results showed the enhanced chemotaxis, phagocytosis and secretion of nitric oxide (NO) and inflammatory cytokines by macrophages when treated with BCPs. However, when chemotaxis and phagocytosis were up-regulated by complement components or opsonized particles, BCPs inhibited these effects. Also, the NO production induced by lipopolysaccharides (LPS) was suppressed by BCPs mildly. Moreover, BCPs had an inhibitory effect on the [Ca] elevation of macrophages. These results suggested that BCPs exerted modulatory effects on macrophage functions, which may contribute to developing novel approaches to treating inflammatory diseases.

Influences of sulfated polysaccharide from pine (Pinus massoniana) pollen on the regulation of [ Ca2+] i in T lymphocytes / 中国药理学通报

Aim Tostudytheinfluencesofsulfated polysaccharides ( SPPM60-D) on the regulation of free calcium concentration ( [ Ca2+] i ) of T lymphocytes of mice in vitro and explore the mechanisms involved. Methods Polysaccharides(PPM60)wereextracted from masson pine pollen with hot water and 60% etha-nol. PPM60-D was separated and purified from PPM60 with Sephacryl S-400HR. Sulfated polysaccharides ( SPPM60-D ) were derivated by chlorosulfonic acid-pyridine method and the [ Ca2+] i of T lymphocytes were measured by fluorescence spectrophotometer. IL-2 and IL-4 were measured by ELISA kits. Results ConAandSPPM60-Dcouldincrease[Ca2+]iinT lymphocytes by 211. 5% and 201. 8% respectively ( P<0. 01). 2-APB, LY294002, U73122 and verapamil rather than TAK-242 could significantly inhibit the in-crease of [ Ca2+] i induced by SPPM60-D. SPPM60-D could significantly increase the level of IL-2 and IL-4 in supernatant ( P <0. 01 ) . 2-APB rather than TAK-242 could significantly inhibit the increase of cyto-kines.Conclusion ItisspeculatedthatSPPM60-D could increase [ Ca2+ ] i via TCR/CD3-PI3K-PLC-IP3 R-Ca2+ signal pathway through TCD/CD3 receptor in T lymphocytes so that it could improve the level of IL-2 and IL-4 in supernatant in T lymphocytes.

The effects of calmodulin kinase Ⅱ inhibitor on hypertrophic cardiac myocytes / 中华急诊医学杂志

Objective To investigate the effect of the calmodulin kinase Ⅱ Inhibitor KN-93 on L-typecalcium current(ICa,L)and intracellular calcium concentration([Ca2+]i)in hypertrophic cardiac myocytes.Methods Forty-eight female New Zealand white rabbits were randomized(random number)into four groups(12 animals in each group):the sham operation group(sham group),the left ventricular hypertrophy group(LVH group),the myocardial hypertrophy + KN-93 group(KN-93 group),and the myocardial hypertrophy + KN-92 group(KN-92 group).Myocardial hypertrophy in the rabbits was established by coarctation of the abdominal aorta.In the sham group,the abdominal aorta was dissociated without coarctation.Eight weeks after coarctation,single ventricular myocytes were isolated by enzymaticdissociation,and ICa,L was recorded using perforated-patch recording(PPR)techniques.[Ca2+]i was measured using single-cell calcium imaging with the fluorescence calcium indicator dye fura-2/AM.Results Cardiac hypertrophy was successfully established after 8 weeks of coarctation of the abdominal aorta.The peak ICa,L in the LVH group and the sham group was(1.38 ± 0.3)nA and(0.87 ± 0.1)nA at 0 mV,respectively(P ＜0.01,n =12).There was no significant difference in Ica,L density between the LVH group and the sham group[(6.7 ±1.0)pA/pF vs.(6.3±0.7)pA/pF; P≥0.05,n=12].The addition of either KN-92(0.5 μmol/L)or KN-93(0.5 μmol/L)to the perfusing solution caused a modest steady-state inhibition of peak ICaL(9.4％ ±2.8％,KN-92; 10.5％ ±3％,KN-93)(P≥0.05,n =12)at 0 mV.However,at a higher concentration(1 μmol/L),KN-93 more potently inhibited peak ICa,L(40％±4.9％)compared to KN-92(13.4％ ± 3.7％ ; P ＜ 0.01,n =12).Resting[Ca2+]i levels in fura-2-loaded myocytes isolated from the sham,LVH,KN-92,and KN-93 groups were(98 ± 12.3)nmol/L,(154 ± 26.2)nmol/L,(147 ± 29.6)nmol/L,and(108 ± 21.2)nmol/L,respectively.Conclusions The CaMK Ⅱ specific inhibitor,KN-93,can effectively block ICa,L and reduce intracellular calcium overload in hypertrophic cardiac myocytes.This action may account for the antiarrhythmic effect of KN-93 in hypertrophic ventricular myocardium.

[Ca2+]i homeostasis and caspase-3 gene expression in verapamil-induced retinal pigment epithelium cells apoptosis in vitro / 国际眼科杂志(Guoji Yanke Zazhi)

(Ver)-induced human retinal pigment epithelium (RPE) cells apoptosis.hours to induce RPE cells apoptosis.The expression of apoptotic effector gene caspase-3 was assessed by reverse transcription polymerase chain reaction (RT-PCR).Single cell was measured using fluorescence indicator Fura-3/AM with MetaFluo4.5/coolsnapfx/IX70 intracellular Ca2+ fluorescence imaging system.RPE cells and it significantly increased after co-cultured with Ver.The fluorescence in resting RPE cells was strong and distributed throughout the cells.The nucleus appeared more fluorescent than the cytoplasm.Calcium fluorescence of RPE cells attenuated after co-cultured with Ver.[Ca2+]i homeostasis might play pivotal roles in Ver-induced RPE cells apoptosis.

Activation of adenosine A_1 receptor inhibits glucose-induced cardiomyocyte hypertrophy / 中国药理学通报

Aim To demonstrate the effects and mechanism of adenosine A1 receptor agonist R(-)-N6-(2-phenylisopropyl) adenosine(R-PIA) on high glucose(HG)-induced myocardial hypertrophy by in vitro cultured myocardial cells from neonatal rats.Methods The protein content was assayed by the method of Lowry. The expression of p-ERK1/2 and ERK1/2 was determined by Western blot.The [Ca~(2+)]I transient changes of cell loaded Fura-2/AM were measured by Till image system.Results 1 μmol·L~(-1) R-PIA and U0126 inhibited similarly HG-induced increase of the protein content and [Ca~(2+)]I transient along with the relative expression of p-ERK1/2.These responses were completely abolished by adenosine A1 receptor antagonist 8-cyclopentyl-1,3-dipropylxanthine(CPDPX).Conclusion Adenosine A1 receptor stimulation significantly inhibits HG-induced myocardial hypertrophy by mediating ERK1/2 pathway and Ca~(2+).

Effect of GBE50 on L-type calcium current and cytosolic[Ca~(2+)]_i in ischemic guinea pig ventricular myocytes / 中国药理学通报

Aim To observe the effect of Ginkgo biloba extract 50(GBE50)on L-type calcium current and cytosolic[Ca~(2+)]_i in ischemic guinea pig ventricular myocytes.Methods Single ventricular myocytes were isolated by enzymatic dissociation. I Ca-L was recorded by whole-cell patch clamp technique in voltage clamp mode.[Ca~(2+)]_i was detected by laser confocal micros-copy and represented by relative fluorescent intensity (FI).Results During ischemia, the peak Ca~(2+) current was reduced, and the I-U curve of I Ca-L was shifted upward.50 mg·L~(-1) GBE50 reversed the change induced by ischemia(n =6, P >0.05).After perfusing ischemic solution for 12 min, intracellular calcium concentration was increased(n =10, P <0.01).After perfusion with ischemic solution containing 50 mg·L~(-1) GBE50, the increase of intracellular calcium concentration was markedly inhibited(n =10, P >0.05).Conclusion GBE50 can reverse the decrease of I Ca-L and partially inhibit calcium overloading during ischemia.

Long-term effects of oxypurinol on oxidative modification of actin and myocardial contractility in mice with heart failure / 上海交通大学学报（医学版）

Objective To investigate the long-term effects of xanthine oxidase inhibitor,oxypurinol on myocardial contractility of post-ischemic heart failure in mice,and explore the underlying mechanism. Methods One hundred and twenty SV120 mice were randomly assigned into myocardial infarction control group,sham operation group and Oxy treatment group.Post-ischemic heart failure were induced by left anterior descending coronary artery ligation in myocardial infarction control group and Oxy treatment group,and mice in Oxy treatment group and sham operation group were orally administered with 0.5 mmol/L Oxy each day.Nine to eleven months after treatment,echocardiography was performed in all groups.Trabeculae from the right ventricle of mice were dissected for assessment of changes in excitation-contraction coupling.Sarcomere length was measured by laser diffraction.Intracellular free Ca~(2+) concentration([Ca~(2+)]_I)was detected with fluorescent dye Fura-2,which was microinjected iontophoretically into cells. Steady-state force-[Ca~(2+)]_I was achieved by addition of ryanodine and increasing the stimulus frequency to induce tetanization,and the relationship between myocardial contractility and intracellular Ca~(2+) transients was analysed.Besides,Western blotting was performed to determine the oxidation of myofilament proteins. Results Long-term oral administration of oxypurinol significantly improved myocardial contraction function and reduced ventricular wall thickness.Programming of excitation-contraction coupling was significantly improved,and maximal Ca~(2+) activated force(F_(max))in steady-state wag also significantly increased.Western blotting revealed the oxidative modification of actin in mice of Oxy treatment group was significantly inhibited compared with that of myocardial infarction control group. Conclusion Long-term treatment with Oxy improves the cardiac contraction function and boosts the cardiac force dramatically in post-ischemia heart failure.The increase in contraction is the result of increased myofilament Ca~(2+) responsiveness.Thus,antioxidant oxypurinol,by preventing oxidative damage to contractile proteins,can augment contraction with little changes in[Ca~(2+)]_I,represents new class of inotropic agents with advantages of reducing Ca~(2+) overload,and offers new promises in management of heart failure in the future.

Clinical significance of changes of RBC [Ca2 +]i levels in the neonates with hypoxic-ischemic encephalopathy / 中国小儿急救医学

Objective To explore the role of RBC[Ca2+]i levels in pathogenesis of hypoxic-ischemic encephalopathy (HIE) in neonates. Methods Twenty-eight neonates with moderate and severe HIE hospitalizeal from Jun. 2002 to Mar. 2006 were enrolled the study. The neonates with HIE were given routine treatment and Nimodipine for 7～10 days. Blood samples were collected before treatment and at 72 hours,7～10 days after treatment respectively. The levels of RBC [Ca2+]i were measured by Fura-2/AM. Twenty healthy full-term neonates were studied as controls. Results (1) The levels of RBC [Ca2+] i in the neonates with moderate and severe HIE were significantly higher than that in control group at every time points( P＜0. 05 ,P＜0.01). (2) the levels of RBC[Ca2+]i in the neonates with moderate and severe HIE peaked at 72 hours after treatment,and were still significantly higher than that of control group at 7～10 days after treatment(P＜0. 05). (3) In the neonates with HIE,RBC[Ca2+ ]i levels correlated positively with the severity of HIE ( r = 0. 447, P＜ 0. 05 ). Conclusion RBC [Ca2+ ] i levels are closely associated with pathogenesis of HIE, and may play an important role in the pathogenesis of HIE. Evaluating RBC [ Ca2+] i levels in neonate after birth may provide clinical clues for the early diagnosis and prognosis assessment of HIE.

Influence of the 15-HETE on cytosolic [ Ca2+] i of the rabbit pulmonary artery smooth muscle cells

Extracellular Ca2+ influx was blocked by L-type Ca2+ channel blocker nifedipine to observe the effects of 15-hydroxyeicosatetraenoic acid on the constriction of rabbit pulmonary artery rings and on the changes of Ca2+ level in the rabbit pulmonary artery smooth muscle cells, and further to investigate the mechanism of the calcium mobilization induced by the 15-HETE under hypoxic conditions. The effect of extracellular Ca2+ on tension of the rabbit PA rings was also studied. Nifedipine (10 µ mol/L) had no effect on 1 µ mol/L 15-hydroxyeicosatetraenoic acid induced vasoconstriction under normoxic and hypoxic conditions. Intracellular Ca2+ increased markedly in the 15-HETE group (cells were exposed to 1 µ mol/L 15-HETE for 8 min during culture) compared to the control group (P < 0.05). The study demonstrated that the 15-HETE could induce the elevation of Ca2+ in the pulmonary artery smooth muscle cells and the elevated calcium came from the release of the intracellular calcium.

Effects of Haloperidol on Ca2+i Change in HIT T-15 Insulinoma Cells / 대한정신약물학회지

OBJECTIVE: The purpose of this study was to investigate the effects of haloperidol on [Ca2+]i in hamster insulinoma cells (HIT T-15). METHODS: [Ca2+]i levels were measured by calcium imaging techniques, and membrane potential ionic currents were recorded using conventional patch-clamp methods. RESULTS: Haloperidol induced a transient [Ca2+]i increase, which was abolished by the removal of extracellular Ca2+ or pretreatment with Ca2+ channel blockers (nimodipine and mibefradil). Haloperidol depolarized the membrane potential and inhibited the ATP-sensitive K+ (KATP) channels. Sigma receptor agonists, (+)-SKF10047 and ifenprodil, induced a transient [Ca2+]i increase similar to haloperidol. BD1047, a sigma receptor antagonist, completely blocked the [Ca2+]i increase induced by haloperidol. Haloperidol inhibited the KCl-induced [Ca2+]i increase and voltage-dependent Ca2+ currents. Sigma receptor agonists [(+)-SKF10047, ifenprodil] also inhibited the KCl-induced [Ca2+]i increase. CONCLUSION: Our results suggest that haloperidol induces depolarization, which increases [Ca2+]i by voltage-gated Ca2+ currents via the closing of KATP channels. Haloperidol also inhibits KCl-induced [Ca2+]i increases in the same manner. These effects of haloperidol seemed to be mediated by sigma receptors, which might be linked to the pathogenesis of haloperidol-induced diabetes mellitus.

Effects and Mechanism of Adenosine A_1 Receptor Agonist on Isoproterenol Induced Hypertrophy in Cultured Neonatal Rats Myocardial Cells / 中华高血压杂志

Objective To demonstrate the inhibitory effect of adenosine A_1 receptor agonist R(-)-N6-(2-phe- nylisopropyl) adenosine (R-HA) and cross-talk between adenosine A_1 receptor and CaMKII on Isoproterenol (Iso)- induced hypertrophy in cultured myocardial cells in neonatal rats.Methods The protein synthesis was determined by incorporation of [~3H]-leucine into myocyte protein.The expression of CaMK Ⅱ ? B was determined by Western- blot.The [Ca~(2+)]i transient was measured in myocytes loaded with fura-2 by the spectrofluorometric method. Results R-PIA (1?mol/L) inhibited Iso(10 ?mol/L)-induced increase of [~3 H-]-leucine incorporation [(R-PIA: 974.8?58.6) vs (Iso:1220.8?240.5) count per min per well,P

Lysophosphatidylcholine Attenuates Endothelium-dependent Relaxation Responses through Inhibition of ACh-induced Endothelial Ca2+i Increase

Lysophosphatidylcholine (LPC), which accumulates in atherosclerotic arteries, has been reported to inhibit endothelium-dependent relaxation (EDR) in many different species. However, the underlying mechanism of LPC-induced inhibition of EDR is still uncertain. In the present study, we measured simultaneously both isometric tension and cytosolic free Ca2+ ([Ca2+]i) in rabbit carotid strips, and examined the effect of LPC on tension and [Ca2+]i. In carotid strips with intact-endothelium, high K+ (70 mM) increased both tension and [Ca2+]i, and cumulative addition of acetylcholine (ACh) from 0.1 to 10microM induced dose dependent increase of [Ca2+]i with concomitant relaxation. In the presence of L-NAME (0.1 mM), ACh increased [Ca2+]i without affecting the amplitude of high K+-induced tension. These ACh-induced change of [Ca2+]i and tension was abolished by removal of endothelium or 10 nM 4-DAMP (muscarinic receptor antagonist) pretreatment. Pretreatment of LPC (10microM) inhibited ACh (10microM)-induced change of tension and [Ca2+]i in endothelium-intact carotid artery. On the other hand, LPC had no effect on ACh-induced change of tension and [Ca2+]i in endothelium denuded artery. In Ca2+-free external solution, ACh transiently increased [Ca2+]i, and pretreatment of LPC significantly inhibited ACh-induced transient [Ca2+]i change. Based on the above results, it may be concluded that LPC inhibits the ACh-induced [Ca2+]i change through inhibition of Ca2+ mobilization in vascular endothelial cells, resulting in decreased production of NO and concomitant inhibition of endothelium-dependent vascular relaxation.

To Explore the Double-labeling Method of Monitoring the GHRP Regulatory Function on [Ca~(2+)]i and NO on Real Time in Cardiomyocytes Under LSCM / 医学研究杂志

Objective To explore the double-labeling method of monitoring the GHRP regulatory function on [Ca2+]i and NO in cardiomyocytes of rats on real time under LSCM.Methods The reformed constant-flow Langendorff system and enzyme-dissociated was used to isolate cardiomyocytes.[Ca2+]i and NO in the cardiomyocytes of SD rats were double-labeled by their molecular probe Rhod-2/AM and DAF-FM/DA,respectively to monitor the regulatory function of GHRP on [Ca2+]i and NO on real time by LSCM.Results Ca2+ signal showed a red fluorescence and NO showed a green fluorescence while the overlapping of the two signals showed a yellow-green fluorescence by this system,and the similar effect presents in both double-labeled state and the single labeled one:GHRP induced a transient[Ca2+]i increase then followed by a plateau phase while there was not significant change in NO signal system after GHRP stimulation under the LSCM in the cardiomyocytes of rats.Conclusions After having established the double-labeling method we monitored the GHRP regulatory function on [Ca2+]i and NO on real time in cardiomyocytes of rats under LSCM causing the [Ca2+]i biphasic increase while no significant change in NO signal system.

Research of mechanisms of swainsonine-induced apoptosis in the human gastric carcinoma cell line SGC-7901 / 中国临床药理学与治疗学

AIM: To investigate the effects and mechanisms of swainsonine-induced apoptosis on SGC-7901 cells. METHODES: After being treated with swainsonine, effective dose and median inhibition concentration (IC50) of swainsonine to SGC-7901 cells were examined by MTT assay. Cell cycle distribution and apoptotic rates were analyzed by flow cytometry. Expression of p53, c-myc and Bcl-2 were determined by immunocyto- chemical method, and the concentration of Ca2+ intra-cellular ([Ca2+]i ) was measured by the laser scanning confocal microscope (LSCM). RESULTS: Swainsonine inhibited cell growth of SGC-7901 in vitro, IC50 of 24 h was 0.84 μg·ml-l, and complete inhibition concentration of swainsonine was 6.2 μg·ml-l. Treated with swainsonine at the concentrations of 0.5, 1.5 and 4.5 μg·ml-l for 24 h, the expression of apoptosis inhibiting gene p53 and bcl-2 decreased, and apoptotic trigger gene c-myc increased (P<0.05), as well as [Ca2+]i overloading, SGC-7901 cell was induced to apoptosis in the end. The percentage of S phase were 38.8%, 39.7% and 29.6%, respectively (20.0% in control group and 23.2% in 5-Fu group), the percentage of G2/M phase were 4.5%, 1.7% and 5.3%, respectively (5.5% in control group and 9.0% in 5-Fu group), and the percentage of G1/M phase was not altered. SGC-7901 cells were treated by swainsonine at the concentrations of 0.5, 1.5 and 4.5 μg·ml-l for 24 h. Compared with the control group, the percentage of S phase were increased and that of G2/M cells were decreased significantly in treatment groups (P<0.01). CONCLUSION: Swainsonine can inhibit the cell proliferation and induce apoptosis of SGC-7901 cells, the mechanisms of swainsonine-induced apoptosis may related with [Ca2+]i overloading and expression of apoptosis-related genes.

The effect of 15-HETE on the cytosolic Ca2+i in rabbit pulmonary artery smooth muscle cells (PASMC) / 中国药理学通报

Aim: The purpose of this study was to observe the effect of 15-HETE on rabbit pulmonary artery (PA) vasoconstriction after removing extracellular Ca2+ and on [Ca2+]i in PASMCs and to discuss the mechanisms of cytosolic Ca2+ mobilization induced by 15-HETE. Methods: We used tention studies of PA rings to observe the effect of L-type Ca2+ channel blocker and non-Ca2+ solution on PA vasoconstriction induced by 15-HETE. Then we used laser-scanning confocal microscope to investigate [Ca2+]i signaling in cultured PASMCs. Results: L-type Ca2+ channel blocker and non-Ca2+ solution had no effect on 15-HETE induced vasoconstriction in normoxic and hypoxic rabbit PA rings. The increase of [Ca2+]i was shown in 15-HETE group cells and the change in [Ca2+]i induced by 15-HETE was significantly different from that of control. Conclusion: 15-HETE may activate Ca2+ release from intracellular stores and raise [Ca2+]i in PASMCs.

Effects of Gingko biloba extract on glutamate-induced [ Ca2+ ]i changes in cultured cortical astrocytes after hypoxia/reoxygenation, H2O2 or L-glutamate injury / 药学学报

Aim To investigate glutamate-induced [ Ca2 + ] i changes in cultured rat neonatal cortical astrocytes after hypoxia/reoxygenation, H2O2 or high concentration of L-glutamate injury. In the meantime, the effects of Gingko biloba extract (GbE) were examined. Methods [ Ca2+ ]i changes in astrocytes were monitored by laser scanning confocal microscopy with the Ca2+ sensitive fluorescent probe [ Ca2 + ] i, but decrease by ( 3.3 ± 1.6) %, (81 ± 11 ) % and ( 81 ± 7 ) %, respectively. Pretreatment with H2O2 or high concentration of L-glutamate injury were ( 135 ± 98 ) %, ( 117 ± 93 ) % and ( 89 ± 36) %,different injury. Conclusion Hypoxia/reoxygenation, H2O2 and high concentration of L-glutamate impaired astrocytes' response to exogenous L-glutamate, and then bidirectional communication between astrocytes and neurons could not take place. GbE could improve the abnormal responses and maintain the normal function of astroglical network. These effects support that GbE has potential beneficial actions against brain injury.

Na+-Ca2+ Exchange Curtails Ca2+ before Its Diffusion to Global Ca2+i in the Rat Ventricular Myocyte

In the heart, Na+-Ca2+ exchange (NCX) is the major Ca2+ extrusion mechanism. NCX has been considered as a relaxation mechanism, as it reduces global [Ca2+]i raised during activation. However, if NCX locates in the close proximity to the ryanodine receptor, then NCX would curtail Ca2+ before its diffusion to global Ca2+i. This will result in a global [Ca2+]i decrease especially during its ascending phase rather than descending phase. Therefore, NCX would decrease the myocardial contractility rather than inducing relaxation in the heart. This possibility was examined in this study by comparing NCX-induced extrusion of Ca2+ after its release from SR in the presence and absence of global Ca2+i transient in the isolated single rat ventricular myocytes by using patch-clamp technique in a whole-cell configuration. Global Ca2+i transient was controlled by an internal dialysis with different concentrations of BAPTA added in the pipette. During stimulation with a ramp pulse from +100 mV to -100 mV for 200 ms, global Ca2+i transient was suppressed only mildly, and completely at 1 mmol/L, and 10 mmol/L BAPTA, respectively. In these situations, ryanodine-sensitive inward NCX current was compared using 100micromol/L ryanodine, Na+ depletion, 5 mmol/L NiCl2 and 1micromol/L nifedipine. Surprisingly, the result showed that the ryanodine-sensitive inward NCX current was well preserved after 10 mmol/L BAPTA to 91 % of that obtained after 1 mmol/L BAPTA. From this result, it is concluded that most of the NCX-induced Ca2+ extrusion occurs before the Ca2+ diffuses to global Ca2+i in the rat ventricular myocyte.

Effects of Naftopidil' ramification-BWYJ on intracellularlar free Ca~(2+) in smooth cells / 中国临床药理学与治疗学

AIM: To observed the effects of BWYJ (a naftopidil ramification) on intracellularlar free Ca~(2+)([Ca~(2+)]_i) in smooth cells (SMCs) in order to further explore its vasodilative mechanisms. METHODS: The [Ca~(2+)]_i was determined with the Fura-2/AM loaded SMCs in aorta of rabbit, and the effects of BWYJ on the elevation induced by NA, and high potassium and 5-HT were observe. RESULTS: In the Fura-2/AM loaded SMCs, BWYJ had no effect on the resting [Ca~(2+)]_i, but it reduced the increase of [Ca~(2+)]_i induced by NA and 5-HT, and there was no influence on the increase of [Ca~(2+)]_i induced by high potassium. CONCLUSION: The vasodilative mechanisms of BWYJ may be related to its inhibitive effects on the Ca~(2+)-influx and Ca~(2+)-release mediated by ?_1- and 5-HT_(2A) receptors. It inhibits the release of intracellular calcium, and the result is it decrease the [Ca~(2+)]_i in SMCs.

Influnence of ET-1 on [Ca~(2+)]i in cultured bovine trabecular meshwork cells in vitro / 西安交通大学学报(医学版)

Objective To find out the method of ET-1 in regulating trabecular meshwork cell(TMC) contraction and to explore new effective drug treating glaucoma with little side-effects.Methods TMCs were obtained through the cultured tissue,and then loaded with Fluo-3/AM,the value of [Ca~(2+)]i was obtained by dynamically scanning the changes of intracellular fluorescent intensity after the application of different concentration of ET-1.Results The application of ET-1(10~(-9),10~(-8)and 10~(-7)mol/L),led to an increase in([Ca~(2+)]i.) Especially,the application of 10~(-8) mol/L ET-1 led to a significant increase in [Ca~(2+)]i: from(327.50)?(24.57) to 373.60?40.18(n=8,P