Amiloride ; analogs & derivatives ; chemistry ; metabolism ; Binding Sites ; Genotype ; Hepacivirus ; genetics ; metabolism ; Humans ; Magnetic Resonance Spectroscopy ; Molecular Dynamics Simulation ; Protein Structure, Tertiary ; Viral Proteins ; antagonists & inhibitors ; metabolism

Cell-penetrating peptide (CPP) can be used in pharmaceutics as a highly efficient drug delivery transporter. In this study, four tumor cell lines (MCF-7, MDA-MB-231, C6, and B16F10) were used to observe the uptake of fluorescein isothiocyanate (FITC) labeled CPP and the effects of time and concentration of CPP on cell penetration was studied. The CPP exocytosis on C6 cell line was observed, and its exocytosis kinetics was described by zero order equation. In addition, low-temperature condition (4 degrees C) and endocytosis inhibitors were utilized to investigate the mechanism of CPP uptake by cells. Low-temperature condition did not show significantly inhibition on CPP uptake. Heparin, a membrane glycoprotein receptor inhibitor, showed strong inhibition effect (only 3%-10% of the control) on CPP uptake. Chlorpromazine, chloroquine and 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) showed little effect on CPP uptake. This study indicated that CPP penetration had little selectivity on cell type, but the amount and rate of CPP penetration into cells were related to the type of cell lines. The adsorption of CPP on cell membrane induced by sulfate proteoglycan plays an important role on CPP penetration.
Adsorption ; Amiloride ; analogs & derivatives ; pharmacology ; Cell Line, Tumor ; Cell Membrane ; metabolism ; Cell-Penetrating Peptides ; administration & dosage ; metabolism ; pharmacokinetics ; Chloroquine ; pharmacology ; Chlorpromazine ; pharmacology ; Dose-Response Relationship, Drug ; Exocytosis ; Heparin ; analogs & derivatives ; metabolism ; pharmacology ; Humans ; Proteoglycans ; metabolism ; Temperature ; Time Factors

The aim of this study was to evaluate the effect of dimethyl amiloride (DMA), a specific inhibitor of Na(+)/H(+) exchanger-1 (NHE-1), on intracellular pH value (pHi), proliferation and apoptosis of HL-60/ADM cells in vitro. After treatment with DMA at different doses, pHi of HL-60 and HL-60/ADM cell lines were determined by using pH-sensitive fluorescence dye BECEF-AM; the rate of growth inhibition of cells was detected with MTT assay; cell cycle was detected by flow cytometric DNA analysis; cell apoptosis was observed with terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL). The results showed that pHi in HL-60/ADM cells was higher than that in HL-60 cells. After treatment with DMA at different doses, pHi decreased, the rate of growth inhibition and the rate of apoptotic cells in HL-60/ADM cells were all higher than those in HL-60 cells. Meanwhile, after treatment with DMA during 100 micromol/L to 150 micromol/L, the increase amplitude of G(0)/G(1) phase cells and the decrease amplitude of S + G(2)/M cells in HL-60/ADM cells were higher than those in HL-60 cells. It is concluded that by causing intracellular acidification, the NHE-1-specific inhibitor DMA inhibits proliferation of HL-60/ADM cells and induces apoptosis of HL-60/ADM cells, and the degree of this growth inhibition of HL-60/ADM cells is higher than that of HL-60 cells.
Amiloride ; analogs & derivatives ; pharmacology ; Apoptosis ; drug effects ; Cell Cycle ; drug effects ; Cell Proliferation ; drug effects ; Doxorubicin ; pharmacology ; Drug Resistance, Neoplasm ; HL-60 Cells ; Humans ; Hydrogen-Ion Concentration ; Sodium-Hydrogen Exchangers ; antagonists & inhibitors

The effects of 5-(N,N-dimethyl)amiloride (DMA) (a blocker of Na(+)/H(+) exchanger or Na(+)/Ca(2+) exchanger) on calcium transient and cell contraction in isolated ventricular myocytes in normal rats and rats with myocardial hypertrophy were examined using ion imaging system with a charge coupled digital camera (CCD camera). Loading myocytes with Fura-2, electrically triggered Ca(2+) transients and cell shortening were measured simultaneously. The results showed that 10 micromol/L DMA increased Ca(2+) transient and cell shortening from 209.60+/-54.96 and 3.07+/-0.97 micrometer to 238.50+/-80.41 and 4.07+/-1.02 micrometer, respectively (P<0.05), which was completely abolished by application of KB-R7943, a specific reverse mode Na(+)/Ca(2+) exchanger blocker. After blocking L-type Ca(2+) channels by nicardipine, DMA also enhanced Ca(2+) transient and cell shortening. In rats with myocardial hypertrophy, DMA showed the common pharmacologic profile as in normal rats but more intense stimulating effects on Ca(2+) transient and cell contraction. The results suggest that DMA increase Ca(2+) transient and cell contraction via stimulating reverse mode Na(+)/ Ca(2+) exchange, and the stimulating effect is more pronounced in rats with myocardial hypertrophy than in normal ones.
Amiloride ; analogs & derivatives ; pharmacology ; Animals ; Calcium ; metabolism ; Cardiomyopathy, Hypertrophic ; drug therapy ; Heart Ventricles ; cytology ; Myocardial Contraction ; drug effects ; Myocytes, Cardiac ; metabolism ; Rats ; Rats, Wistar ; Sodium-Calcium Exchanger ; antagonists & inhibitors ; pharmacology

BACKGROUND/AIMS: JX-594 is an oncolytic virus derived from the Wyeth vaccinia strain that causes replication-dependent cytolysis and antitumor immunity. Starting with a cross-examination of clinical-trial samples from advanced hepatocellular carcinoma patients having high levels of aldosterone and virus amplification in JX-594 treatment, we investigated the association between virus amplification and aldosterone in human cancer cell lines. METHODS: Cell proliferation was determined by a cell-counting-kit-based colorimetric assay, and vaccinia virus quantitation was performed by quantitative polymerase chain reaction (qPCR) and a viral plaque assay. Also, the intracellular pH was measured using a pH-sensitive dye. RESULTS: Simultaneous treatment with JX-594 and aldosterone significantly increased viral replication in A2780, PC-3, and HepG2 cell lines, but not in U2OS cell lines. Furthermore, the aldosterone treatment time altered the JX-594 replication according to the cell line. The JX-594 replication peaked after 48 and 24 hours of treatment in PC-3 and HepG2 cells, respectively. qPCR showed that JX-594 entry across the plasma membrane was increased, however, the changes are not significant by the treatment. This was inhibited by treatment with spironolactone (an aldosterone-receptor inhibitor). JX-594 entry was significantly decreased by treatment with EIPA [5-(N-ethyl-N-isopropyl)amiloride; a Na+/H+-exchange inhibitor], but aldosterone significantly restored JX-594 entry even in the presence of EIPA. Intracellular alkalization was observed after aldosterone treatment but was acidified by EIPA treatment. CONCLUSIONS: Aldosterone stimulates JX-594 amplification via increased virus entry by affecting the H+ gradient.
Aldosterone/*pharmacology ; Aldosterone Antagonists/pharmacology ; Amiloride/analogs & derivatives/pharmacology ; Animals ; Carcinoma, Hepatocellular/blood/virology ; Cell Line, Tumor ; Humans ; Hydrocortisone/blood ; Hydrogen-Ion Concentration ; Liver Neoplasms/blood/virology ; Neuroprotective Agents/pharmacology ; Oncolytic Virotherapy ; Rabbits ; Spironolactone/pharmacology ; Vaccinia virus/*drug effects/genetics/metabolism/*physiology ; Virus Replication/*drug effects

Amiloride and benzamil showed antinocicepitve effects in several pain models through the inhibition of acid sensing ion channels (ASICs). However, their role in neuropathic pain has not been investigated. In this study, we investigated the effect of the intrathecal amiloride and benzamil in neuropathic pain model, and also examined the role of ASICs on modulation of neuropathic pain. Neuropathic pain was induced by L4-5 spinal nerve ligation in male Sprague-Dawley rats weighing 100-120 g, and intrathecal catheterization was performed for drug administration. The effects of amiloride and benzamil were measured by the paw-withdrawal threshold to a mechanical stimulus using the up and down method. The expression of ASICs in the spinal cord dorsal horn was also analyzed by RT-PCR. Intrathecal amiloride and benzamil significantly increased the paw withdrawal threshold in spinal nerve-ligated rats (87%+/-12% and 76%+/-14%, P=0.007 and 0.012 vs vehicle, respectively). Spinal nerve ligation increased the expression of ASIC3 in the spinal cord dorsal horn (P=0.01), and this increase was inhibited by both amiloride and benzamil (P<0.001 in both). In conclusion, intrathecal amiloride and benzamil display antinociceptive effects in the rat spinal nerve ligation model suggesting they may present an alternative pharmacological tool in the management of neuropathic pain at the spinal level.
Acid Sensing Ion Channels/genetics/metabolism ; Amiloride/*analogs & derivatives/pharmacology/*therapeutic use ; Analgesics/pharmacology/*therapeutic use ; Animals ; Disease Models, Animal ; Male ; Neuralgia/*drug therapy ; RNA, Messenger/metabolism ; Rats ; Rats, Sprague-Dawley ; Reverse Transcriptase Polymerase Chain Reaction ; Spinal Cord/metabolism ; Transcription, Genetic/drug effects