OBJECTIVETo explore the effect of ouabain on intracellular Ca(2+) concentration ([Ca(2+)]i) in thoracic aorta vascular smooth muscle cells (VSMCs) in vitro.

METHODSPrimary SD rat thoracic aorta VSMCs were cultured by tissue adherent method and identified by immunochemistry. The binding ability between ouabain and VSMCs was detected by autoradiography, and fluo 3-AM (a Ca(2+) fluorescent probe) was employed to investigate whether ouabain affected VSMCs within a short period of time. The effect of a truncated fragment of the sodium pump α2 subunit was assayed in antagonizing the effect of ouabain on [Ca(2+)]i in the VSMCs.

RESULTSWithin the concentration range of 0.1-100 nmol/L, ouabain was found to dose-dependently bind to the VSMCs. Different concentrations of ouabain (0-3200 nmol/L) caused a transient, dose-dependent increase in [Ca(2+)]i in the VSMCs, which was antagonized by the application of the truncated fragment of sodium pump α2 subunit.

CONCLUSIONSElevations in [Ca(2+)]i in the VSMCs can be the cytological basis of high ouabain-induced hypertension. The truncated fragment of the sodium pump α2 subunit can antagonize ouabain-induced increase of [Ca(2+)]i in the VSMCs, which provides a clue for understanding the pathogenesis of and devising a therapeutic strategy for high ouabain-induced hypertension.

Animals ; Aorta, Thoracic ; cytology ; Calcium ; metabolism ; Cells, Cultured ; Cytoplasm ; metabolism ; Muscle, Smooth, Vascular ; cytology ; Myocytes, Smooth Muscle ; drug effects ; metabolism ; Ouabain ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Sodium-Potassium-Exchanging ATPase

A growing number of researches have shown that ouabain can regulate mammalian sperm function and male reproduction by modulating the sperm motility, capacitation and acrosome reaction in vitro. This study further examined the relationship between ouabain and asthenozoospermia. In this study, the rat was intraperitoneally injected with ouabain at different concentrations (low-dose ouabain group: 12.5 μg/kg body weight per day, and high-dose ouabain group: 25 μg/kg body weight per day) for 30 days to establish the asthenozoospermia model. The sperms from 60 males with normal fertility were incubated with ouabain of gradient concentrations (10(-7)-10(-2) mol/L) for 4 h. The sperm motility was evaluated under a microscope. Moreover, the endogenous ouabain (EO) level was determined in seminal plasma of mild or severe asthenozoospermia patients and males with normal fertility by competitive inhibition ELISA. The results showed that the sperm motility was significantly diminished in the rats treated with different concentrations of ouabain. The number of motile sperms (grades a and b) was decreased greatly in a time- and dose-dependent manner in 10(-5)-10(-2) mol/L ouabain groups (P<0.01), while no obvious change in sperm motility was observed in 10(-7)-10(-6)mol/L groups even for 4-h incubation (P>0.05). Furthermore, the EO level was significantly increased in asthenozoospermia patients as compared with that in males with normal fertility (25.27±1.71 μg/L in mild asthenozoospermia patients, 26.52±1.82 μg/L in severe asthenozoospermia patients, 19.31±1.45 μg/L in normal fertility men) (P<0.01). In conclusion, rat asthenozoospermia was successfully established by intraperitoneal injection of ouabain, and 10(-5) mol/L ouabain was sufficient enough to inhibit sperm motility in vitro. Moreover, EO, a normal constituent of seminal plasma, was highly expressed in asthenozoospermia males as compared with normal fertility ones.
Animals ; Asthenozoospermia ; chemically induced ; metabolism ; physiopathology ; Disease Models, Animal ; Dose-Response Relationship, Drug ; Humans ; Injections, Intraperitoneal ; Male ; Ouabain ; metabolism ; pharmacology ; toxicity ; Rats ; Rats, Sprague-Dawley ; Semen ; metabolism ; Sperm Motility ; drug effects ; physiology ; Spermatozoa ; drug effects ; physiology ; Time Factors

To study the antiarrhythmic effect of the newly developed alpha/beta-blocker TJ0711, a variety of animal models of arrhythmia were induced by CaCl2, ouabain and ischemia/reperfusion. Glass microelectrode technique was used to observe action potentials of right ventricular papillary muscle of guinea pig. The onset time of arrhythmia induced by CaCl2 was significantly prolonged by TJ0711 at 0.75, 1.5 and 3 mg x kg(-1) doses. TJ0711 (1.5 and 3 mg x kg(-1)) can significantly shorten the ventricular tachycardia (VT) and ventricular fibrillation (VF) duration, the incidence of VF and mortality were significantly reduced. On ischemia-reperfusion-induced arrhythmic model, TJ0711 (0.25, 0.5, 1 and 2 mg x kg(-1)) can significantly reduce the ventricular premature contraction (PVC), VT, VF incidence, mortality, arrhythmia score with a dose-dependent manner. At the same time, rats serum lactate dehydrogenase (LDH) and creatine kinase (CK) activities decreased significantly by TJ0711 (1 and 2 mg x kg(-1)). Ouabain could cause arrhythmia in guinea pigs, when TJ0711 (0.375, 0.75, 1.5 and 3 mg x kg(-1)) was given, the doses of ouabain inducing a variety of arrhythmia PVC, VT, VF, cardiac arrest (CA) were significantly increased with a dose-dependent manner. In the TJ0711 0.1-30 micromol x L(-1) concentration range, guinea pig right ventricular papillary muscle action potential RP (rest potential), APA (action potential amplitude) and V(max) (maximum velocity of depolarization) were not significantly affected. APD20, APD50 and APD90 had a shortening trend but no statistical difference with the increase of TJ0711 concentration. TJ0711 has antiarrhythmic effect on the sympathetic nerve excitement and myocardial cell high calcium animal arrhythmia model. Myocardial action potential zero phase conduction velocity and resting membrane potential were not inhibited by TJ0711. APD20, APD50 and APD90 were shortened by TJ0711 at high concentration. Its antiarrhythmic action mechanism may be besides the action of blocking beta1 receptor, may also have a strong selective blocking action on alpha1 receptor and reducing intracellular calcium concentration.
Action Potentials ; drug effects ; Adrenergic alpha-Antagonists ; administration & dosage ; pharmacology ; Adrenergic beta-Antagonists ; administration & dosage ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; administration & dosage ; pharmacology ; Arrhythmias, Cardiac ; blood ; chemically induced ; etiology ; pathology ; physiopathology ; Calcium Chloride ; Creatine Kinase ; blood ; Dose-Response Relationship, Drug ; Female ; Guinea Pigs ; Heart Ventricles ; cytology ; Lactate Dehydrogenases ; blood ; Male ; Myocardial Reperfusion Injury ; complications ; Myocytes, Cardiac ; drug effects ; physiology ; Ouabain ; Papillary Muscles ; cytology ; Phenoxypropanolamines ; administration & dosage ; pharmacology ; Random Allocation ; Rats ; Rats, Sprague-Dawley

OBJECTIVEPeriplocin is an active digitalis-like component from Cortex Periplocae, which has been widely used in the treatment of heart diseases in China for many years. According to the recommendations on the cardiovascular effect of periplocin from in vivo experiments, subsequent in vitro experiments are greatly needed for the global assessment of periplocin. The objective of this study is to investigate the cell proliferation effect and the mechanism of periplocin on endothelial cells.

METHODSThe proliferative activity of periplocin (0.4, 2, 10, 50, 250 micromol/L; 6, 12, 24, 48, 72 h) was investigated by a comparison with the well-reported cardiac glycoside, ouabain, on mouse cardiac microvascular endothelial cells (CMEC). 3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) and 5-bromo-2-deoxyuridine (BrdU) assays were used to evaluate cell proliferation and viability. Subsequently, cDNA microarray experiments were performed on periplocin- (50 micromol/L) and ouabain- (50 micromol/L) treated cells, and data was analyzed by ArrayTrack software.

RESULTSPeriplocin could increase cell viability to a level lower than ouabain in the MTT analysis, but decrease LDH release simultaneously. The BrdU incorporation assay showed an increase in cell proliferation with 2-50 micromol/L periplocin. Genes related to protein serine/threonine kinase were the most significantly enriched in the 160 genes identified in periplocin versus the control. In the 165 genes regulated by periplocin versus ouabain, GTP-binding was the most altered term.

CONCLUSIONSThe results demonstrated the proliferation action of periplocin on CMEC. Meanwhile, its lower cytotoxicity compared to ouabain provides a new insight into the treatment of heart failure.

Animals ; Animals, Newborn ; Cardiac Glycosides ; pharmacology ; Cardiotonic Agents ; pharmacology ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; genetics ; Cells, Cultured ; Coronary Vessels ; drug effects ; metabolism ; physiology ; Drug Evaluation, Preclinical ; Endothelial Cells ; drug effects ; metabolism ; physiology ; Gene Expression Profiling ; Gene Expression Regulation ; drug effects ; Mice ; Microvessels ; drug effects ; metabolism ; physiology ; Models, Biological ; Myocardium ; metabolism ; Oligonucleotide Array Sequence Analysis ; Ouabain ; pharmacology ; Saponins ; pharmacology

OBJECTIVETo assess the binding activity of polypeptide containing human Na+, K+-ATPase alpha1 subunit M1-M2 extracellular segment (HES1 derivative).

METHODSHES1 derivative was synthesized by Fmoc method and purified by high-performance liquid chromatography-mass spectrometry, and its binding activity was identified by radioligand binding assay.

RESULTS3H-ouabain and synthetic HES1 derivative showed some binding activity with the equilibrium dissociation constant (KD) of 24.58 nmol/L, with the the receptor density of 492.43 fmol x mg(-1) pro. and IC50 of 3.078 x 10(-7) mol/L.

CONCLUSIONHES1 derivative can bind to ouabain and has the potential of becoming an effective therapeutic agent.

Binding Sites ; drug effects ; Extracellular Space ; metabolism ; Humans ; Ouabain ; chemistry ; pharmacology ; Peptides ; chemistry ; Protein Binding ; Sodium-Potassium-Exchanging ATPase ; chemistry ; genetics ; metabolism

The aim of this study was to investigate the effects of ouabain and some specific signal pathway inhibitors on growth regulation in various kinds of leukemia cell lines and to explore the role of signal pathways participating in proliferation or apoptosis of leukemia cells induced by ouabain. By using MTT, the survival rates of leukemia cell lines were observed after utilizing ouabain and the specific signal pathway inhibitors. The expressions of Na(+), K(+)-ATPase alpha1 subunit of leukemia cells were evaluated by RT-PCR and Western blot. The results showed that low concentration of ouabain (10 nmol/L) could increase the survival rates of lymphocytic leukemia Jhhan cell line and megakaryocytic leukemia M07e cell line, and could up-regulate the expression of Na(+), K(+)-ATPase alpha1 subunit. Proliferation of these leukemia cells induced by ouabain could be inhibited by PP2 and PD98059 with different extents. It is concluded that Na(+), K(+)-ATPase plays an important role in signal transductions through binding to CTS (ouabain), and they can activate complex signal pathways regulating the growth of leukemia cells. The proliferation effects of cells promoted by ouabain are mediated by activation of Src kinase and ERK1/2 dependent signaling pathway.
Cell Line, Tumor ; Cell Proliferation ; drug effects ; Humans ; Leukemia ; metabolism ; Ouabain ; pharmacology ; Signal Transduction ; drug effects ; Sodium-Potassium-Exchanging ATPase ; metabolism

OBJECTIVECardiotonic steroids (CTS) can bind to Na+, K+ -ATPase to activate complex intracellular signaling cascades regulating the proliferation and apoptosis of cells. The aim of this study was to investigate the effects of ouabain at different concentrations on growth regulation in various kinds of leukemia cell lines and explore the pathogenesis of leukemia, the functions of Na+, K+ -ATPase as a signal transduction conductor and its effects on cell growth.

METHODSUsing the MTT assay, the survival rates of leukemia cell lines were observed 6, 12 and 24 hrs after treatment with 1 or 10 nmol/L ouabain. The expression of Na+, K+ -ATPase alpha1 subunit of leukemia cells was detected by Western blot.

RESULTSThe MTT results showed that ouabain at 1 nmol/L or 10 nmol/L induced proliferation of lymphocytic leukemia B95 and Jhhan cell lines, as well as megakaryocytic leukemia M07e and Meg01 cell lines. Ouabain at 1 nmol/L or 10 nmol/L increased the expression of Na+, K+ -ATPase alpha1 subunit. There were significant differences in the proliferation and the expression of Na+, K+ -ATPase alpha1 subunit of the leukemia cell lines between the ouabain treatment and the blank control groups 24 hrs after ouabain treatment (P<0.05). The proliferation effect of leukemia cell lines was in a direct proportion with the ouabain concentration and incubation time.

CONCLUSIONSNa+, K+ -ATPase plays an important role in signal transductions. Through binding to ouabain, Na+, K+ -ATPase may regulate proliferation of leukemia cell lines of different origins. Ouabain at 1 nmol/L or 10 nmol/L may induce proliferation of lymphocytic leukemia cell lines (B95, Jhhan) and megakaryocytic leukemia cell lines (M07e, Meg01), and the proliferation effect was in a direct proportion with the concentration and incubation time of ouabain.

Cell Proliferation ; drug effects ; Dose-Response Relationship, Drug ; Humans ; Leukemia ; pathology ; Ouabain ; pharmacology ; Signal Transduction ; Sodium-Potassium-Exchanging ATPase ; analysis ; genetics ; physiology

OBJECTIVE: To evaluate the protective effect of low dose ouabain on injury of cultured spiral ganglion neurons evoked by trophic factors deprived and to explore the mechanism. METHOD: Spiral ganglion neurons were cultured in vitro for 7 days, and then exposed to Neurobasal medium + B27 supplement, Neurobasal medium only or Neurobasal medium + 10 nmol/L ouabain, respectively. After 48 h exposed to different medium, spiral ganglion neurons were stained by FITC labeled Annexin-V and PI, then apoptosis index were calculated using fluorescent microscope and flow cytometry, respectively. In addition, spiral ganglion tissues were cultured for 48 h to evaluate dendrite growth of spiral ganglion neurons in each group. Immunocytochemistry were performed to detect the level of Bcl-2 in each group at 6 h and 12 h. RESULT: Spiral ganglion neurons exposed to Neurobasal medium +10 nmol/L ouabain have a similar apoptosis index compare with that of Neurobasal medium + B27 supplement, but a much lower apoptosis index than that of Neurobasal medium only. In addition, dendrite growth of spiral ganglion neurons exposed to Neurobasal medium +10 nmol/L ouabain was much longer than that of Neurobasal medium only. Bcl-2 level increased in spiral ganglion neurons exposed to Neurobasal medium + 10 nmol/L ouabain at 6 h. CONCLUSION Low dose of ouabain protects injury of spiral ganglion neurons evoked by trophic factors deprived in vitro. This effect may mediated by increasing the level of Bcl-2.
Animals ; Apoptosis ; drug effects ; Cell Survival ; drug effects ; Cells, Cultured ; Ouabain ; administration & dosage ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Spiral Ganglion ; drug effects ; pathology

In order to explore the activity of a peptide containing rat sodium pump α2 subunit M1-M2 extramembrane fragment (RES2 derivative) in vitro, the peptide (Leu-Ala-Ala-Met-Glu-Asp-Glu-Pro-Ser-Asn-Asp-Asn-Gly-Gly-Gly-Ser) was synthesized by peptide synthesizer with Fmoc method and purified by high performance liquid chromatography (HPLC). Its binding activity was identified by radioligand-receptor binding assay (RRA) and its bioactivity was measured by erythrocyte (86)Rb uptake. The results of saturation binding experiment and competitive binding experiment showed that the synthesized RES2 derivative had the capability to bind to (3)H-ouabain. The dissociation constant (K(d)) was 38.46 nmol/L and IC(50) was 6.353 nmol/L. Erythrocyte (86)Rb uptake experiment showed that the RES2 derivative blocked the inhibitory effect of ouabain on the sodium pump on erythrocyte membrane in a dose-dependent manner. The results showed that the RES2 derivative is capable of binding to ouabain and improving the activity of sodium pump on erythrocyte membrane, suggesting that the RES2 derivative might become an effective antihypertensive drug in the future.
Amino Acid Sequence ; Animals ; Chromatography, High Pressure Liquid ; Erythrocyte Membrane ; drug effects ; Ouabain ; pharmacology ; Peptide Fragments ; metabolism ; Rats ; Sodium-Potassium-Exchanging ATPase ; metabolism

AIMTo study the effect of Na+, K(+)-ATPase inhibition by ouabain on growth and death of vascular endothelial cells ECV304 and involved mechanisms.

METHODSGrowth inhibition of ouabain on ECV304 cells was analyzed using MTT assay. The feature of cell death was studied by Hoechst 33342/PI staining, transmission electron microscopy and DNA agarose gel electrophoresis in ECV304 cells treated with ouabain. The mRNA expression of Na+, K(+)-ATPase alpha1, beta1-subunit was examined by reverse transcription PCR (RT-PCR).

RESULTSOuabain inhibited the growth of ECV304 cells in a dose and time-dependent manner. 10 micromol/L ouabain treated for 24 hours could stimulate the necrosis of ECV304 cells; When treated with 0.1 micromol/L ouabain for 24-48 hours, the cells showed obviously defluxion, the loss of cell-cell contacts, nuclear chromatin condensation, chromatin margination and DNA fragmentation. Na+, K(+)-ATPase alpha1-subunit mRNA expression was significantly up-regulated in ECV304 cells treated with ouabain while the beta1-subunit expression conversely showed a significant decrease.

CONCLUSIONOuabain could up-regulate Na+, K(+)-ATPase alpha1-Subunit expression and reduce beta1-Subunit expression which mediated signal transduction and decreased cell-cell adhesions and induced ECV304 cells death.

Cell Death ; drug effects ; Cell Line ; Endothelial Cells ; cytology ; drug effects ; metabolism ; Humans ; Ouabain ; pharmacology ; Sodium-Potassium-Exchanging ATPase ; metabolism