Calcium ion exists extensively in cells as the second messenger, and calcium channel blocker (CCB) is widely used to treat cardiac, skeletal muscular diseases. With the advances in the investigation of human sperm calcium channel, CCB has been proved to affect not only the shape, activation and acrosome reaction, but also the function of human sperm, which may afford a new approach to male contraception.
Calcium Channel Blockers ; pharmacology ; Calcium Channels ; physiology ; Humans ; Male ; Spermatozoa ; drug effects ; physiology

AIMTo study the effects of fluoride (F-) on ionized calcium ([Ca2+]i) and calcium channel in osteoblast-like cell (OBLs).

METHODSInvestigating [Ca2+]i was by fluorospectrophotometry and recording the calcium currents of OBLs was using whole patch-clamp technique.

RESULTSThe addition of fluoride to the medium made a rapid and significant increase in free [Ca2+]i, especially in 100 ng F- /ml group. There were significances between control group and 50, 100 ng F- /ml groups. And 25 ng/ml F- could stimulate OBLs calcium channel open. Compared with control group, fluoride could significantly increase the amplitudes of calcium currents (P < 0.01), furthermore the activation was in dose-dependent manner.

CONCLUSIONFluoride can make calcium channel open and then increase the concentrations of [Ca2+]i.

Calcium ; physiology ; Calcium Channels ; physiology ; Cell Line ; Fluorides ; toxicity ; Humans ; Osteoblasts ; cytology ; drug effects ; metabolism ; Patch-Clamp Techniques

OBJECTIVETo investigate the effect of ketamine on the high-voltage-activated calcium currents (ICa(HVA)) in rat hippocampal neurons.

METHODSNeurons were cultured from Wistar rat hippocampus. ICa(HVA) was recorded using whole-cell patch clamp technique. After application with ketamine at different concentrations (10, 30, 100, 300, and 1000 μmol/L), the effect of ketamine on ICa(HVA) was evaluated.

RESULTSICa(HVA) was inhibited by ketamine in a concentration-dependent manner. Ketamine at 10 μmol/L showed no effect on ICa(HVA). Four concentrations of ketamine (30, 100, 300,and 1000 μmol/L) reduced the peak ICa(HVA) currents by (17.5 ∓ 4.5)%, (25.5 ∓ 6.9)%, (38.5 ∓ 4.1)%, and (42.3 ∓ 4.6)% respectively,with a mean half maximal inhibitory concentration of 68.2 μmol/L and Hill coefficient of 0.47. The maximal activation membrane potential was shifted to (5.3 ∓ 0.8) from (5.4 ∓ 0.9). The half maximal activation membrane potential of inactivation curve was shifted from(-26.7 ∓ 3.9) mV to(-32.8 ∓ 4.2) mV.

CONCLUSIONKetamine can remarkably inhibit calcium currents in the central neurons,which may explain at least partly the action of ketamine on central nervous system.

Animals ; Calcium Channels ; drug effects ; physiology ; Cells, Cultured ; Hippocampus ; drug effects ; physiology ; Ketamine ; pharmacology ; Membrane Potentials ; drug effects ; Neurons ; drug effects ; physiology ; Rats ; Rats, Wistar

Action Potentials ; drug effects ; Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Animals ; Biphenyl Compounds ; pharmacology ; Calcium Channels, L-Type ; drug effects ; physiology ; Heart Atria ; cytology ; drug effects ; Myocytes, Cardiac ; drug effects ; physiology ; Potassium Channels ; drug effects ; physiology ; Rabbits ; Tetrazoles ; pharmacology

OBJECTIVETo investigate the effects of Hg2+ on voltage-dependent calcium channels and intracellular free calcium in trigeminal ganglion neurons of rats and explore the toxicity mechanism of Hg2+ on these neurons.

METHODSWhole cell patch-clamp technique was used to determine ICa of voltage-dependent calcium channels in trigeminal ganglion neurons of rats. Intracellular free calcium was measured to explore [Ca2+]i dynamic changes from a single cell level by laser scanning confocal microscopy and fluorescence probe techniques.

RESULTS0.01, 0.10, 1.00 and 10.00 micromol/L Hg2+ could reduce voltage-dependent calcium channel currents ICa by (1.80+/-0.32)%, (23.04+/-9.46)%, (58.20+/-7.90)% and (82.00+/-5.77)% in trigeminal ganglion neurons. The inhibiting effects reached their maximum in 5 minutes and could not be reversed significantly during wash with Hg2+-free solution. Also, 0.01, 0.10 and 1.00 micromol/L Hg2+ increased intracellular free calcium concentrations by (2.50+/-0.83)%, (82.81+/-35.36)% and (222.70+/-62.48)% in trigeminal ganglion neurons. Pre-administrated trigeminal ganglion neurons with nifedipine for 10 minutes could decrease the effects and delay the effecting time.

CONCLUSIONThe inhibition of Hg2+ on the voltage-dependent calcium channel currents ICa depends on voltage-dependent calcium channels. And the increase of intracellular free calcium concentration in trigeminal ganglion neurons induced by Hg2+ is related to the release of intracellular stored calcium. However, the relationship between them needs further investigation.

Animals ; Calcium ; metabolism ; Calcium Channels ; drug effects ; metabolism ; physiology ; Cells, Cultured ; Female ; Male ; Mercury ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Trigeminal Ganglion ; cytology ; drug effects ; metabolism ; physiology

OBJECTIVETo observe the effect of Maixinkang Capsule (MXK) on Ca2t concentration and mitochondrial membrane potential in liver cells of ApoE(-/-) mice.

METHODSLiver cells from ApoE(-/-) mice were separated using collagenase digestive method. After the primary cells were cultured for 8 days in vitro, the concentration of 10% MXK contained rat's serum was added into the culture fluid. The Ca2+ concentration and mitochondrial membrane potential in liver cells after 48-hr culture were measured by confocal laser scanning microscopy with Flou-3 and Jc-1 as probes.

RESULTSMXK could decrease Ca2+ concentration in liver cells, which was significantly different to that in the control group (P < 0.01). Meanwhile, MXK could significantly improve mitochondrial membrane potential in liver cells (P < 0.01). There was no obvious dose-effect relationship shown in both effects of MXK.

CONCLUSIONMXK can decrease Ca2+ concentration and improve the mitochondrial membrane potential in liver cells of ApoE(-/-) mice so as to regulate the lipids and prevent the occurrence and development of hyperlipemia and atherosclerosis.

Animals ; Animals, Newborn ; Apolipoproteins E ; genetics ; Calcium Channels ; drug effects ; Hepatocytes ; physiology ; Membrane Potentials ; Mice ; Mice, Knockout ; Mitochondrial Membranes ; physiology

Action Potentials ; drug effects ; physiology ; Animals ; Cadmium ; toxicity ; Calcium Channels, L-Type ; physiology ; Myocytes, Cardiac ; drug effects ; physiology ; Rats ; Rats, Sprague-Dawley

This study was designed to investigate the effects of polyamines on mechanical contraction and voltage-dependent calcium current (VDCC) of guinea-pig gastric smooth muscle. Mechanical contraction and calcium channel current (I(Ba)) were recorded by isometric tension recording and whole-cell patch clamp technique. Spermine, spermidine and putrescine inhibited spontaneous contraction of the gastric smooth muscle in a concentration-dependent manner. Spermine (2 mM) reduced high K+ (50 mM)-induced contraction to 16+/-6.4% of the control (n=9), and significantly inhibited I(Ba) in a reversible manner (p<0.05; IC50=0.8 mM). Pre- and post-treatment of tissue with spermine (2-5 mM, n=10) also inhibited acetylcholine (10 micrometer)-induced phasic contraction to 5+/-6.4% of the control. Inhibitory effect of spermine on I(Ba) was observed at a wide range of test potentials of current/voltage (I/V) relationship (p<0.05), and steady-state activation of I(Ba) was shifted to the right by spermine (p<0.05). Spermidine and putrescine (1 mM each) also inhibited I(Ba) to 51+/-5.7% and 81+/-5.3% of the control, respectively. And putrescine (1 mM) inhibited I(Ba) at whole tested potentials (p<0.05) without significant change of kinetics (p<0.05). Finally, 5 mM putrescine also inhibited high K+ -induced contraction to 53+/-7.1% of the control (n=4). These findings suggest that polyamines inhibit contractions of guinea-pig gastric smooth muscle via inhibition of VDCC.
Pyloric Antrum/*drug effects/physiology ; Potassium/pharmacology ; Polyamines/*pharmacology ; Muscle, Smooth/*drug effects/physiology ; Muscle Contraction/*drug effects ; Male ; Guinea Pigs ; Female ; Calcium Channels/drug effects/physiology ; Calcium/metabolism ; Animals

BACKGROUND/AIMS: Tamoxifen is a widely used anticancer drug for breast cancer with frequent gastrointestinal side effects. Changes in gastrointestinal motility is associated with altered activities of membrane ion channels. Ion channels have important role in regulating membrane potential and cell excitability. This study was performed to investigate the effects of tamoxifen on the membrane ionic currents in colonic smooth muscle cells. METHODS: Murine colonic smooth muscle cells were isolated from the proximal colon using collagenase, and the membrane currents were recorded using a whole-cell patch clamp technique. RESULTS: Two types of voltage-dependent K+ currents were recorded (A-type and delayed rectifier K+ currents). Tamoxifen inhibited both types of voltage-dependent K+ currents in a dose-dependent manner. However, tamoxifen did not change the half-inactivation potential and the recovery time of voltage-dependent K+ currents. Chelerythrine, a protein kinase C inhibitor or phorbol 12, 13-dibutyrate, a protein kinase C activator did not affect the voltage-dependent K+ currents. Guanosine 5'-O-(2-thio-diphosphate) did not affect the tamoxifen-induced inhibition of voltage-dependent K+ currents. Tamoxifen inhibited voltage-dependent Ca2+ currents completely in whole-test ranges. CONCLUSIONS: These results suggest that tamoxifen can alter various membrane ionic currents in smooth muscle cells and cause some adverse effects on the gastrointestinal motility.
Animals ; Antineoplastic Agents, Hormonal/*pharmacology ; Calcium Channels/drug effects ; Colon/*drug effects/physiology ; English Abstract ; In Vitro ; Membrane Potentials ; Mice ; Myocytes, Smooth Muscle/*drug effects/physiology ; Potassium Channels/*drug effects ; Tamoxifen/*pharmacology

OBJECTIVETo investigate the effect of 17 beta-estradiol (E2) on T-type calcium currents (ICaT) in spermatogenic cells.

METHODSCa2+ currents were obtained in acutely dissociated mouse spermatogenic cells by the whole-cell patch clamp technique and the effects of E2 on ICaT were observed.

RESULTSE2 at the concentrations of 1, 10 and 100 micromol/L significantly inhibited ICaT in the mouse spermatogenic cells, with the KC50 value of 8.89 micromol/L and the inhibition rates of (13.48 +/- 1.86) %, (28.98 +/- 2.70) and (52.93 +/- 3.42)%, respectively (n = 6, P < 0.05). E2 of 100 micromol/L significantly changed the activation and inactivation of ICaT: the half activation potential (Va 1/2) and the activation steepness factor (Ka) from ( -48.94 +/- 0.22) mV and (5.19 +/- 0.19) mV to (-54.34 +/- 1.02) mV and (6.02 +/- 0.84) mV ( n = 5, P < 0.05) , and the half inactivation potential (Vi 1/2) and the inactivation steepness factor (Ki) from (-56.51 +/- 0.13) mV and (3.36 +/- 0.11) mV to (-61.78 +/- 0.50) mV and (4.25 +/- 0.37) mV, respectively (n = 5, P < 0.05).

CONCLUSIONE2 has a significant inhibitory effect on ICaT in mouse spermatogenic cells in a con-centration-dependent manner.

Animals ; Calcium Channels, T-Type ; physiology ; Cells, Cultured ; Dose-Response Relationship, Drug ; Estradiol ; pharmacology ; Male ; Membrane Potentials ; drug effects ; Mice ; Patch-Clamp Techniques ; Spermatids ; cytology ; drug effects ; physiology