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

We studied medium alkalinization in Salvia miltiorrhiza suspension cultures treated with salicylic acid and the effect of Ca2+ in this process through application of calcium channel antagonists (Verapamil, LaCl3, LiCl, 2-APB) and ionophore A23187. The results show that salicylic acid could induce significant medium alkalinization in S. miltiorrhiza culture. Verapamil and LaCl3 or LiCl and 2-APB, two different groups of calcium channel antagonist, significantly inhibited the medium alkalinization induced by salicylic acid. However, the suppression effect of verapamil or LaCl3 on medium alkalinization induced by salicylic acid was higher than that of LiCl or 2-APB. When two types of calcium channel inhibitor (LaCl3 and 2-APB) were used together, the medium alkalinization induced by salicylic acid was completely suppressed and even reduced the pH in medium. On the other hand, A23187 could promote the medium alkalinization. Based on the results above, we speculated that salicylic acid could induce significant medium alkalinization in S. miltiorrhiza culture, depending on the calcium from both extracell and intracell. Moreover, calcium from extracell plays a more dominant role in this process. Reveal of relationship in this research between Ca2+ and medium alkalinization can provide theory evidence for mechanism of the plant secondary metabolism.
Calcimycin ; pharmacology ; Calcium ; chemistry ; Calcium Channel Blockers ; pharmacology ; Calcium Ionophores ; pharmacology ; Cell Culture Techniques ; Culture Media ; chemistry ; Salicylic Acid ; pharmacology ; Salvia miltiorrhiza ; metabolism ; Verapamil ; pharmacology

OBJECTIVETo observe the effects of isoflurane combined with diltiazem on human sperm motility in vitro and to investigate its possible mechanism.

METHODSTen normal semen samples were collected, each divided into 9 groups, one as the control and the others treated in vitro with different concentrations of diltiazem or diltiazem +4.2% isoflurane for 1 hour. Sperm motility was observed with the computer-assisted sperm analyzer.

RESULTSCompared with the control, diltiazem significantly decreased sperm motility at the concentrations of 0.01 g/L, 0.04 g/L, 0.2 g/L and 1 g/L in a dose-dependent manner, and reduced it to approximately 0% at 1 g/L. When combined with 4.2% isoflurane, diltiazem obviously increased sperm motility at 0.01 g/L, markedly decreased it at 0.2 g/L, and effected no significant difference at 0.04 g/L and 1 g/L as compared with the corresponding concentrations of diltiazem alone.

CONCLUSIONThe stimulating effect of isoflurane on sperm motility may be associated with the calcium ion channel in sperm. When completely blocked by diltiazem, this effect may turn into an inhibition of sperm motility.

Adult ; Calcium Channel Blockers ; pharmacology ; Diltiazem ; pharmacology ; Drug Antagonism ; Humans ; Isoflurane ; pharmacology ; Male ; Sperm Motility ; drug effects

AIMTo discover new regulators of potassium channel, an in vitro assay based on DiBAC4 (3) to determine the fluorescence was established for high throughput screening.

METHODSA cell-based 96-well format fluorescence assay using DiBAC4 (3) in cultured PC12 cells was described. Cells were loaded with 5 mumol.L-1 DiBAC4 (3) and incubated at 37 degrees C for 30 min before adding KCl or several known potassium channel regulators. The cellular DiBAC4 (3) fluorescence responce was then detected. The fluorescence changes can be used to evaluate membrane potential changes, which are determined mainly by potassium channels.

RESULTSExtracellular high K(+)-induced depolarization and several potassium channel blockers including 4-AP, TEA, E-4031, glibenclamide, quinidine and nifedipine all evoked increases in DiBAC4 (3) fluorescence response. The potassium channel opener, cromakalim, evoked decrease in DiBAC4 (3) fluorescence response. The fluorescence changes of 4-AP, TEA, glibenclamide, nifedipine and cromakalim were in a concentration-dependent manner. In 76 compounds screened by using the established DiBAC4 (3)-based assay, 9 compounds were found to change the fluorescence dose-dependently. Patch clamp technique is needed to further testify and screen their actions on potassium currents.

CONCLUSIONThe DiBAC4 (3)-based assay is easily operated, economical and repeatable. So, it can be performed by high throughput screening for potassium channel regulators.

4-Aminopyridine ; pharmacology ; Animals ; Barbiturates ; chemistry ; Calcium Channel Blockers ; pharmacology ; Cromakalim ; pharmacology ; Isoxazoles ; chemistry ; Membrane Potentials ; drug effects ; Nifedipine ; pharmacology ; PC12 Cells ; Patch-Clamp Techniques ; Piperidines ; pharmacology ; Potassium Channel Blockers ; pharmacology ; Potassium Channels ; drug effects ; Pyridines ; pharmacology ; Quinidine ; pharmacology ; Rats

The purpose of the current study was to examine the pharmacokinetic profiles and tissue distribution of clevidipine, an ultra-short-acting calcium antagonist in Beagle dogs and Sprague-Dawley rats, respectively. The pharmacokinetics and biodistribution of its primary metabolite H152/81 were also evaluated. Dogs received intravenous infusion of clevidipine at a dose rate of 17 μg/(kg·min), and rats were given intravenous administration of clevidipine at a dose of 5 mg/kg. Dog plasma and rat tissues were collected and assayed by HPLC-MS/MS. It was found that plasma clevidipine quickly reached the steady state concentration. The terminal half-life was short (16.8 min), pointing out a rapid elimination after the end of the infusion. The total clearance was 5 mL/(min·kg). In comparison, plasma concentration of H152/81 was increased more slowly and was significantly higher than that of clevidipine. After intravenous administration, clevidipine was distributed rapidly into all tissues examined, with the highest concentrations found in the brain, heart and liver. Maximal concentrations of clevidipine were found in most tissues at 10 min post-dosing. However, the proportion of clevidipine distributed in all tissues was quite small (0.042‰) compared to the total administration dose. It was suggested that clevidipine was mainly distributed in blood and it transformed to inactive metabolite rapidly.
Animals ; Calcium Channel Blockers ; pharmacokinetics ; pharmacology ; Dogs ; Dose-Response Relationship, Drug ; Organ Specificity ; drug effects ; Pyridines ; pharmacokinetics ; pharmacology ; Rats

In order to study the roles of HBx and calcium inhibitor verapamil in apoptosis of human normal hepatic cells, L02-off, a pTet-off stably integrated human hepatic cell line was established, in which HBx expression was tightly induced by Doxycycline. The effect of different amounts of HBx and verapamil on apoptosis of human normal hepatic cells was detected. The study showed that apoptosis was triggered by accumulation of intracellular HBx, while verapamil had no effects on the apoptotic process. It was concluded that apoptosis mediated by HBx was dose-dependent but calcium-independent.
Apoptosis/*drug effects ; Calcium/pharmacology ; Calcium Channel Blockers/pharmacology ; Cells, Cultured ; Dose-Response Relationship, Drug ; Hepatitis B Antigens/pharmacology ; Hepatocytes/*cytology ; Trans-Activators/*pharmacology ; Verapamil/*pharmacology

In order to study the roles of HBx and calcium inhibitor verapamil in apoptosis of human normal hepatic cells, L02-off, a pTet-off stably integrated human hepatic cell line was established, in which HBx expression was tightly induced by Doxycycline. The effect of different amounts of HBx and verapamil on apoptosis of human normal hepatic cells was detected. The study showed that apoptosis was triggered by accumulation of intracellular HBx, while verapamil had no effects on the apoptotic process. It was concluded that apoptosis mediated by HBx was dose-dependent but calcium-independent.
Apoptosis ; drug effects ; Calcium ; pharmacology ; Calcium Channel Blockers ; pharmacology ; Cells, Cultured ; Dose-Response Relationship, Drug ; Hepatitis B Antigens ; pharmacology ; Hepatocytes ; cytology ; Humans ; Trans-Activators ; pharmacology ; Verapamil ; pharmacology

Calcium Channel Blockers ; pharmacology ; Cell Survival ; drug effects ; Drug Antagonism ; Humans ; Kidney ; cytology ; drug effects ; Lead ; toxicity

OBJECTIVETo study the cytotoxicity of maitotoxin (MTX) and its protective effects on calcium-channel blocking agents, so as to provide the data for control and treatment of MTX poisoning.

METHODSCytotoxicity was measured by MTT detecting system, and cytoplasmic free [Ca(2+)]i was measured by F-4500 fluorometry.

RESULTSIncubation with 8 ng/ml MTX for 3 h reduced the survival ratio of LLC-PK(1) cells. The response was found in a time- and concentration-dependent manner, with significant differences as compared with the control group. The MTX-induced increase in [Ca(2+)]i was inhibited by Verapamil and Nifedipine at 5 x 10(-5) mol/L and 1 x 10(-4) mol/L respectively. Both of them significantly reduced the death of the LLC-PK(1) cells.

CONCLUSIONSCytotoxicity of MTX may be caused by the elevated intracellular [Ca(2+)]i. Calcium-channel blocking agents could protect LLC-PK(1) cells from injury by MTX.

Animals ; Calcium ; metabolism ; Calcium Channel Blockers ; pharmacology ; Drug Antagonism ; LLC-PK1 Cells ; Marine Toxins ; toxicity ; Nifedipine ; pharmacology ; Oxocins ; Swine ; Verapamil ; pharmacology

The effects of hepatic ischemia/reperfusion (1/R) injuries on hepatocellular viability and store-operated calcium current (Isoc) in isolated rat hepatocytes and the effects of 2-APB on store-operated calcium current (Isoc) in isolated rat hepatocytes after hepatic ischemia/reperfusion injuries were studied. Hepatic ischemia and reperfusion injury model was established and whole cell patch-clamp techniques were used to investigate the effects of 2-APB on Isoc. The results showed that ischemia/reperfusion injuries could significantly reduce hepatocellular viability and further increase Isoc in hepatocytes and 2-APB (20, 40, 60, 80, 100 micromol/L,) produced a concentration-dependent decrease of Isoc with IC50 value of 64. 63 +/- 10.56 micromol/L, (n = 8). It was concluded that ischemia/reperfusion injuries could reduce hepatocellular viability, probably through increased Isoc in hepatocytes and 2-APB had a protective effect on ischemia/reperfusion-induced liver injury, probably though inhibiting Isoc.
Boron Compounds/*pharmacology ; Calcium Channel Blockers/*pharmacology ; Calcium Channels/drug effects ; Cell Separation ; Hepatocytes/metabolism ; Liver/*blood supply ; Liver/metabolism ; Rats, Sprague-Dawley ; Reperfusion Injury/*metabolism