This paper aimed to explore the effects of Duzhong Decoction(DZD)-containing serum on the proliferation and osteoblast differentiation of MC3T3-E1 cells through L-type voltage-gated calcium channels(L-VGCCs). L-VGCCs inhibitors, nifedipine and verapamil, were used to block L-VGCCs in osteoblasts. MC3T3-E1 cells were divided into a control group, a low-dose DZD-containing serum(L-DZD) group, a medium-dose DZD-containing serum(M-DZD) group, a high-dose DZD-containing serum(H-DZD) group, a nifedipine group, a H-DZD + nifedipine group, verapamil group, and a H-DZD + verapamil group. The CCK-8 method was used for cell proliferation analysis, alkaline phosphatase(ALP) assay kits for intracellular ALP activity measurement, Western blot for protein expression level in cells, real-time fluorescence quantitative PCR technology for intracellular mRNA expression level determination, fluorescence spectrophotometer for free Ca~(2+) concentration determination in osteoblasts, and alizarin red staining(ARS) for mineralized nodule formation in osteoblasts. The experimental results show that compared to the control group, DZD groups can promote MC3T3-E1 cell proliferation, ALP activity, and mineralized nodule formation, increase intracellular Ca~(2+) concentrations, and upregulate the protein expression of bone morphogenetic protein 2(BMP2), collagen Ⅰ(COL1), α2 subunit protein of L-VGCCs(L-VGCCα2), and the mRNA expression of Runt-related transcription factor 2(RUNX2), and BMP2. After blocking L-VGCCs with nifedipine and verapamil, the intervention effects of DZD-containing serum were inhibited to varying degrees. Both nifedipine and verapamil could inhibit ALP activity, reduce mineralized nodule areas, and downregulate the expression of bone formation-related proteins. Moreover, the effects of DZD-containing serum on increasing MC3T3-E1 cell proliferation, osteoblast differentiation, and Ca~(2+) concentrations, upregulating the mRNA expression of osteoprotegerin(OPG) and protein expression of phosphorylated protein kinase B(p-Akt) and phosphorylated forkhead box protein O1(p-FOXO1), and upregulating phosphatase and tensin homolog(PTEN) expression were reversed by nifedipine. The results indicate that DZD-containing serum can increase the Ca~(2+) concentration in MC3T3-E1 cells to promote bone formation, which may be mediated by L-VGCCs and the PTEN/Akt/FoxO1 signaling pathway, providing a new perspective on the mechanism of DZD in treating osteoporosis.
Animals ; Osteoblasts/metabolism* ; Cell Proliferation/drug effects* ; Cell Differentiation/drug effects* ; Mice ; Drugs, Chinese Herbal/pharmacology* ; Calcium Channels, L-Type/genetics* ; Alkaline Phosphatase/genetics* ; Serum/chemistry* ; Cell Line ; Osteogenesis/drug effects* ; Bone Morphogenetic Protein 2/genetics*

OBJECTIVE: To study hesperetin-induced vasorelaxation after depolarizing contraction in human umbilical veins (HUVs) to elucidate the role of L-type Ca²⁺ channel (LTCC) and related signaling pathway. METHODS: Isometric tension recording was performed in HUV rings pre-contracted with K⁺. Hesperetin relaxing mechanism was investigated using a LTCC opener (BayK8644) and blockers of cyclic nucleotides and phosphodiesterases (PDEs). Whole-cell patch-clamping in A7r5 cells, a rat vascular smooth muscle cell line, was performed to study the effect of hesperetin on LTCC current. RESULTS: After depolarizing precontraction, hesperetin induced HUV relaxation concentration-dependently and endothelium-independently; 1 mmol/L hesperetin reduced denuded HUV ring tension by 68.7% ± 4.3% compared to matching vehicle, osmolality, and time controls (P<0.0001). Importantly, hesperetin competitively inhibited BayK8644-induced contraction, shifting the half maximal effective concentration of BayK8644 response from 1.08 nmol/L [95% confidence interval (CI) 0.49-2.40] in vehicle control to 11.30 nmol/L (95% CI 5.45-23.41) in hesperetin (P=0.0001). Moreover, hesperetin elicited further vasorelaxation in denuded HUV rings pretreated with inhibitors of soluble guanylyl cyclase, adenylyl cyclase, PDE3, PDE4, and PDE5 (P<0.01), while rings pretreated with PDE1 inhibitors could not be relaxed by hesperetin (P>0.05). However, simultaneously applying inhibitors of soluble guanylyl cyclase and adenylyl cyclase could not inhibit hesperetin's effect (P>0.05). In whole-cell patch-clamping, hesperetin rapidly decreased LTCC current in A7r5 cells to 66.7% ± 5.8% (P=0.0104). CONCLUSIONS Hesperetin diminishes depolarizing contraction of human vascular smooth muscle through inhibition of LTCC, and not cyclic nucleotides nor PDEs. Our evidence supports direct LTCC interaction and provides additional basis for the use of hesperetin and its precursor hesperidin as vasodilators and may lead to future vasodilator drug development as a treatment alternative for cardiovascular diseases.
Hesperidin/pharmacology* ; Humans ; Calcium Channels, L-Type/metabolism* ; Umbilical Veins/physiology* ; Muscle Contraction/drug effects* ; Animals ; Rats ; Calcium Channel Blockers/pharmacology* ; Vasodilation/drug effects* ; Muscle Relaxation/drug effects*

OBJECTIVES: To investigate the effects of quercetin on cuproptosis and L-type calcium currents in the myocardium of diabetic rats. METHODS: Forty SD rats were randomized into control group and diabetic model groups. The rat models of diabetes mellitus (DM) induced by high-fat and high-sugar diet combined with streptozotocin (STZ) injection were further divided into DM model group, quercetin treatment group, and empagliflozin treatment group (n=10). Blood glucose and body weight were measured every other week, and cardiac function of the rats was evaluated using echocardiography. HE staining, Sirius red staining, and wheat germ agglutinin (WGA) analysis were used to observe the changes in myocardial histomorphology, and serum copper levels and myocardial FDX1 expression were detected. In cultured rat cardiomyocyte H9c2 cells with high-glucose exposure, the effects of quercetin and elesclomol, alone or in combination, on intracellular CK-MB and LDH levels and FDX1 expression were assessed, and the changes in L-type calcium currents were analyzed using patch-clamp technique. RESULTS: The diabetic rats exhibited elevated blood glucose, reduced body weight, impaired left ventricular function, increased serum copper levels and myocardial FDX1 expression, decreased L-type calcium currents, and prolonged action potential duration. Quercetin and empagliflozin treatment significantly lowered blood glucose, improved body weight, and restored cardiac function of the diabetic rats, and compared with empagliflozin, quercetin more effectively reduced serum copper levels, downregulated FDX1 expression, and enhanced myocardial L-type calcium currents in diabetic rats. In H9c2 cells, high glucose exposure significantly increased myocardial expressions of FDX1, CK-MB and LDH, which were effectively lowered by quercetin treatment; Elesclomol further elevated FDX1, CK-MB and LDH levels in the exposed cells, and these changes were not significantly affected by the application of quercetin. CONCLUSIONS Quercetin ameliorates myocardial injury in diabetic rats possibly by suppressing myocardial cuproptosis signaling and restoring L-type calcium channel activity.
Animals ; Quercetin/pharmacology* ; Calcium Channels, L-Type/metabolism* ; Diabetes Mellitus, Experimental/metabolism* ; Rats, Sprague-Dawley ; Rats ; Myocytes, Cardiac/drug effects* ; Myocardium/pathology* ; Male

The aim of this study was to investigate the inhibitory effect and the underlying mechanism of ethacrynic acid (EA) on the contraction in mice. BL-420S force measuring system was used to measure the tension of mouse tracheal rings. The whole cell patch clamp technique was utilized to record the channel currents of airway smooth muscle (ASM) cells. The calcium imaging system was used to determine the intracellular Ca concentration ([Ca]) in ASM cells. The results showed that EA significantly inhibited the high K (80 mmol/L) and acetylcholine (ACh, 100 µmol/L)-induced contraction of mouse tracheal rings in a dose-dependent manner. The maximal relaxation percentages were (97.02 ± 1.56)% and (85.21 ± 0.03)%, and the median effective concentrations were (40.28 ± 2.20) μmol/L and (56.22 ± 7.62) μmol/L, respectively. EA decreased the K and ACh-induced elevation of [Ca] from 0.40 ± 0.04 to 0.16 ± 0.01 and from 0.50 ± 0.01 to 0.39 ± 0.01, respectively. In addition, EA inhibited L-type voltage-dependent calcium channel (LVDCC) and store-operated calcium channel (SOCC) currents in ASM cells, and Ca influx. Moreover, EA decreased the resistance of the respiratory system (Rrs) in vivo in mice. These results indicated that EA inhibits LVDCC and SOCC, which results in termination of Ca influx and decreases of [Ca], leading to relaxation of ASM. Taken together, EA might be a potential bronchodilator.
Animals ; Calcium ; metabolism ; Calcium Channels, L-Type ; Enzyme Inhibitors ; pharmacology ; Ethacrynic Acid ; pharmacology ; Mice ; Muscle Contraction ; drug effects ; Muscle, Smooth ; drug effects ; Respiratory System ; cytology ; drug effects

OBJECTIVE: To learn the influence the gentamycin on C57BL/6J mice hear and cochlear hair cell ribbon synapses CaV1.3 calcium protein amount. To explore the relationship between hear loss and its dosage correlation change and significance. METHOD: The fixed amino glucoside to C57BL/6J mice was used to make abdominal cavity injection mold every day. The auditory brain-stem response ABR was used to measure the hear of mice in 7th, 14th, 28th after the injection. Immunofluorescence method was used to observe cochlear basement membrane of hair ribbon synapse CaV1.3 calcium channel proteins in the distribution and expression. Inner hair cells synaptic membrane was immune fluorescent tags with CtbP2 and CaV1. 3. RESULT: With the growth of the injected drugs, ABR threshold increased,but all the hair cells and shape had no obvious change. However the amount of hair rib bon synapse CaV1.3 calcium ion channel proteins in the expression had significant differences (P < 0.01). CaV1.3 calcium ion channel proteins increased slightly lower than normal at 7th day, significantly decreased at 14th day, had increased, increased quantity compare with 14th day, but at 28th day after intraperitoneal injection of gentamicin. CONCLUSION The increasing,decreasing and increasing trend of cochlear hair cells CaV1.3 proteins in the environment of amino glucoside drug toxicity showed that the increase of hair ribbon synapse CaV1.3 proteins may have a compensatory effect on the drug toxicity. With the increase of the drug toxicity effect, this kind of decompensated function could be the listening decline, which may be one of the mechanism of damage to hearing.
Animals ; Calcium Channels, L-Type ; metabolism ; Evoked Potentials, Auditory, Brain Stem ; Gentamicins ; pharmacology ; Hair Cells, Auditory, Inner ; drug effects ; metabolism ; Mice ; Mice, Inbred C57BL ; Proteomics

BACKGROUNDEndometrial carcinoma is one of the most common female tract genital malignant tumors. Nifedipine, an L-type calcium channel antagonist can inhibit cell proliferation of carcinomas. Recent studies indicated that a rise in the free cytosolic calcium ([Ca(2+)](c)) was a potent inducer of autophagy. Here, we investigated the relationship between nifedipine and autophagy in Hec-1A cells.

METHODSCells were cultured with nifedipine (10 µmol/L) and harvested at different times for counting cell number. MTT assay was applied to evaluate the cell viability and transwell assay to reveal cell migration. Apoptotic cells were detected with annexin V/PI assay. Then cells were treated with 3-methyladenine (3-MA) (2.5 mmol/L) for 0, 5, 15, 30, 60, and 120 minutes and the expression of the L-type calcium channel alpha1D (Cav1.3) protein was detected. At last, cells were cultured and assigned to four groups with different treatment: untreated (control group), 10 µmol/L nifedipine (N group), 2.5 mmol/L 3-MA (3-MA group), and 10 µmol/L nifedipine plus 2.5 mmol/L 3-MA (N+3MA group). Autophagy was detected with GFP-LC3 modulation by fluorescent microscopy, and expression of the autophagy-associated proteins (LC3, Beclin1 and P70s6K) by Western blotting and monodansylcadaverine (MDC) labeled visualization.

RESULTSProliferation of Hec-1A cells was obviously suppressed by nifedipine compared with that of the untreated cells for 24, 48, and 96 hours (P = 0.000 for each day). The suppression of migration ability of the nifedipine-treated cells (94.0 ± 8.2) was significantly different from that of the untreated cells (160.00 ± 9.50, P = 0.021). The level of early period cell apoptosis induced by nifedipine was (2.21 ± 0.19)%, which was (2.90 ± 0.13)% in control group (P = 0.052), whereas the late period apoptosis level reached (10.38 ± 0.96)% and (4.40 ± 0.60)% (P = 0.020), respectively. The 3-MA group induced a slight increase in the Cav1.3 levels within 15 minutes, but significantly attenuated the Cav1.3 levels after 30 minutes. There were more autophagic vacuoles labeled by MDC in the N group (20.63 ± 3.36) than the control group (6.29 ± 0.16, P = 0.015). GFP-LC3 localization revealed that the LC3 levels of cells in 3-MA group, N+3MA group, 3-MA group were 2.80 ± 0.29, 2.30 ± 0.17, and 1.80 ± 0.21, respectively. Cells in the N group showed significant augmentation of autophagy (P < 0.05). Western blotting analysis confirmed the down-regulation of LC3 levels in 3-MA group (0.85 ± 0.21) and N+3MA group (1.21 ± 0.12) compared with nifedipine treatment (2.64 ± 0.15, P < 0.05). The annexin-V-FITC/PI assay showed that the level of early period cell apoptosis induced in the N+3-MA group ((11.22 ± 0.91)%) differed significantly from that of the control group ((2.51 ± 0.70)%) and N group ((3.47 ± 0.39)%). Similarly, the late period level of the N+3-MA group ((55.19 ± 2.51)%) differed significantly from that of the control group ((15.81 ± 1.36)%) and the N group ((22.09 ± 2.48)%, P < 0.05). The down-regulated expression of P70s6k and up-regulated expression of the Beclin1 revealed significant differences between the N+3-MA group and control group (P = 0.025; Beclin1: P = 0.015).

CONCLUSIONSProliferation and migration in vitro of endometrial carcinoma Hec-1A cells are significantly suppressed by nifedipine. The nifedipine leads autophagy to oppose Hec-1A cells apoptosis. Autophagy inhibition by 3-MA leads down-regulation of Cav1.3 and enhances nifedipine-induced cell death. The nifedipine-induced autophagy is linked to Beclin1 and mTOR pathways.

Adenine ; analogs & derivatives ; pharmacology ; Apoptosis Regulatory Proteins ; physiology ; Autophagy ; drug effects ; Beclin-1 ; Calcium ; metabolism ; Calcium Channel Blockers ; pharmacology ; Calcium Channels, L-Type ; physiology ; Cell Line, Tumor ; Endometrial Neoplasms ; drug therapy ; pathology ; Female ; Humans ; Membrane Proteins ; physiology ; Nifedipine ; pharmacology ; Signal Transduction ; physiology ; TOR Serine-Threonine Kinases ; physiology

Dendroaspis natriuretic peptide (DNP), a new member of the natriuretic peptide family, is structurally similar to atrial, brain, and C-type natriuretic peptides. However, the effects of DNP on the cardiac function are poorly defined. In the present study, we examined the effect of DNP on the cardiac L-type Ca2+ channels in rabbit ventricular myocytes. DNP inhibited the L-type Ca2+ current (ICa,L) in a concentration dependent manner with a IC50 of 25.5 nM, which was blocked by an inhibitor of protein kinase G (PKG), KT5823 (1 microM). DNP did not affect the voltage dependence of activation and inactivation of ICa,L. The alpha1c subunit of cardiac L-type Ca2+ channel proteins was phosphorylated by the treatment of DNP (1 microM), which was completely blocked by KT5823 (1 microM). Finally, DNP also caused the shortening of action potential duration in rabbit ventricular tissue by 22.3 +/- 4.2% of the control (n = 6), which was completely blocked by KT5823 (1 microM). These results clearly indicate that DNP inhibits the L-type Ca2+ channel activity by phosphorylating the Ca2+ channel protein via PKG activation.
Action Potentials/drug effects ; Animals ; Biological Transport/drug effects ; Calcium/metabolism ; Calcium Channels, L-Type/*metabolism ; Carbazoles/pharmacology ; Cells, Cultured ; Cyclic GMP-Dependent Protein Kinases/antagonists & inhibitors ; Elapid Venoms/*metabolism/pharmacology ; Enzyme Activation ; Heart ; Heart Ventricles/drug effects ; Myocytes, Cardiac/drug effects ; Patch-Clamp Techniques ; Peptides/*metabolism/pharmacology ; Phosphorylation/drug effects ; Rabbits

BACKGROUNDIt has been reported that endogenous or exogenous hydrogen sulfide (H(2)S) exerts physiological effects in the vertebrate cardiovascular system. We have also demonstrated that H(2)S acts as an important regulator of electrophysiological properties in guinea pig papillary muscles and on pacemaker cells in sinoatrial nodes of rabbits. This study was to observe the electrophysiological effects of H(2)S on human atrial fibers.

METHODSHuman atrial samples were collected during cardiac surgery. Parameters of action potential in human atrial specialized fibers were recorded using a standard intracellular microelectrode technique.

RESULTSNaHS (H(2)S donor) (50, 100 and 200 µmol/L) decreased the amplitude of action potential (APA), maximal rate of depolarization (V(max)), velocity of diastolic (phase 4) depolarization (VDD) and rate of pacemaker firing (RPF), and shortened the duration of 90% repolarization (APD(90)) in a concentration-dependent manner. ATP-sensitive K(+) (K(ATP)) channel blocker glibenclamide (Gli, 20 µmol/L) partially blocked the effects of NaHS (100 µmol/L) on human atrial fiber cells. The L-type Ca(2+) channel agonist Bay K8644 (0.5 µmol/L) also partially blocked the effects of NaHS (100 µmol/L). An inhibitor of cystathionine γ-lyase (CSE), DL-propargylglycine (PPG, 200 µmol/L), increased APA, V(max), VDD and RPF, and prolonged APD(90).

CONCLUSIONSH(2)S exerts a negative chronotropic action and accelerates the repolarization of human atrial specialized fibers, possibly as a result of increases in potassium efflux through the opening of K(ATP) channels and a concomitant decrease in calcium influx. Endogenous H(2)S may be generated by CSE and act as an important regulator of electrophysiological properties in human atrial fibers.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester ; pharmacology ; Action Potentials ; drug effects ; Calcium Channel Agonists ; pharmacology ; Calcium Channels, L-Type ; metabolism ; Cystathionine gamma-Lyase ; metabolism ; Electrophysiology ; methods ; Glyburide ; pharmacology ; Heart Atria ; drug effects ; metabolism ; Humans ; Hydrogen Sulfide ; metabolism ; In Vitro Techniques ; KATP Channels ; antagonists & inhibitors ; metabolism ; Sulfides ; pharmacology

It is proved that polydatin has cardioprotection against ischemia-induced arrhythmia, but the electrophysiological mechanism is not clear. The aim of the present study was to investigate the effect of polydatin on action potential (AP) in ventricular papillary muscle and the underlying ionic mechanism in rat using intracellular recording and whole-cell patch clamp techniques. The results showed: (1) In normal papillary muscles, polydatin (50 and 100 µmol/L) shortened duration of 50% repolarization (APD(50)) and duration of 90% repolarization (APD(90)) in a concentration-dependent manner (P<0.01). But polydatin had no effects on resting potential (RP), overshoot (OS), amplitude of action potential (APA) and maximal rate of depolarization in phase 0 (V(max)) in normal papillary muscles (P>0.05). (2) In partially depolarized papillary muscles, polydatin (50 µmol/L) not only shortened APD(50) and APD(90) (P<0.05), but also decreased OS, APA and V(max) (P<0.05). (3) After pretreatment with glibenclamide (10 µmol/L), an ATP-sensitive K(+) channel blocker, the electrophysiological effect of polydatin (50 µmol/L) was partially inhibited. (4) Pretreatment with N(G)-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L), a nitric oxide (NO) synthase inhibitor, failed to abolish the effect of polydatin (50 µmol/L) on AP. (5) Polydatin (25, 50, 75 and 100 µmol/L) decreased L-type Ca(2+) current in ventricular myocytes in a concentration-dependent manner (P<0.05). (6) Polydatin (50 µmol/L) increased ATP-sensitive K(+) current in ventricular myocytes (P<0.05). The results suggest that polydatin can shorten the repolarization of AP in normal papillary muscle and inhibit AP in partially depolarized papillary muscle, which might be related to the blocking of L-type Ca(2+) channel and the opening of ATP-sensitive K(+) channel.
Action Potentials ; drug effects ; Animals ; Calcium Channels, L-Type ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Glucosides ; pharmacology ; Heart Ventricles ; cytology ; KATP Channels ; metabolism ; Male ; Papillary Muscles ; metabolism ; physiology ; Rats ; Rats, Sprague-Dawley ; Stilbenes ; pharmacology

OBJECTIVETo observe the effects of the separate and joint use of salvianolic acid B (SalB) and tetrahydropalmatine (THP) on the L-type calcium channel of rat ventricular myocytes.

METHODSSingle isolated ventricular myocytes of rats were obtained using acute enzymolysis separation. The current of the L-type calcium channel was recorded using whole-cell patch clamp technique. Changes of the current peak value of the calcium channel (the vertical distance between the peak value point after activation of the calcium electric current and the electric current track after complete inactivation) were observed before and after medication.

RESULTSThe inhibition rate of using SalB (at the dose of 1, 10, and 100 micromol/L) alone on the current peak value of the calcium channel was respectively (25.3 +/- 16.4)% (n=4), (44.6 +/- 24.0)% (n=6), and (86.0 +/- 20.4)% (n =4). That of using THP (at the dose of 10, 30, and 100 micromol/L) alone on the current peak value of the calcium channel was respectively (22.2 +/- 6.4)% (n=5), (27.4 +/- 1.6)% (n= 3), and (51.0 +/- 23.0)% (n=9). The inhibition potency of joint use of SalB (1 micromol/L) and THP (10 micromol/L) on the current peak value of the calcium channel was stronger than using SalB (1 micromol/L) alone or THP (10 micromol/L) alone, showing statistical difference ( P< 0.05). Atropine hydrochloric acid (14 mmol/L) could reverse the inhibition of THP on the L-type calcium channel, while strengthening the inhibition of SalB.

CONCLUSIONSBoth SalB and THP showed inhibition on the L-type calcium channel of rat ventricular myocytes. They could generate synergistic effects. Besides, their action mechanisms for regulating the L-type calcium channel were different.

Animals ; Benzofurans ; pharmacology ; Berberine Alkaloids ; pharmacology ; Calcium Channels, L-Type ; metabolism ; Heart Ventricles ; cytology ; Male ; Myocytes, Cardiac ; drug effects ; metabolism ; Patch-Clamp Techniques ; Rats ; Rats, Sprague-Dawley