Swelling-activated chloride currents (ICl.swell) are thought to play a role in several physiologic and pathophysiologic processes and thus represent a target for therapeutic approaches. However, the mechanism of ICl.swell regulation remains unclear. In this study, we used the whole-cell patch-clamp technique to examine the role of protein kinase C (PKC) in the regulation of ICl.swell in human atrial myocytes. Atrial myocytes were isolated from the right atrial appendages of patients undergoing coronary artery bypass and enzymatically dissociated. ICl.swell was evoked in hypotonic solution and recorded using the whole-cell patch-clamp technique. The PKC agonist phorbol dibutyrate (PDBu) enhanced ICl.swell in a concentration-dependent manner, which was reversed in isotonic solution and by a chloride current inhibitor, 9-anthracenecarboxylicacid. Furthermore, the PKC inhibitor bis-indolylmaleimide attenuated the effect and 4α-PDBu, an inactive PDBu analog, had no effect on ICl.swell. These results, obtained using the whole-cell patch-clamp technique, demonstrate the ability of PKC to activate ICl,swell in human atrial myocytes. This observation was consistent with a previous study using a single-channel patch-clamp technique, but differed from some findings in other species.
Anthracenes ; pharmacology ; Chloride Channels ; metabolism ; Chlorides ; agonists ; antagonists & inhibitors ; metabolism ; Culture Media ; metabolism ; pharmacology ; Dose-Response Relationship, Drug ; Evoked Potentials ; drug effects ; physiology ; Heart Atria ; cytology ; drug effects ; metabolism ; Humans ; Hypotonic Solutions ; metabolism ; pharmacology ; Indoles ; pharmacology ; Ion Transport ; drug effects ; Maleimides ; pharmacology ; Myocytes, Cardiac ; cytology ; drug effects ; metabolism ; Patch-Clamp Techniques ; Phorbol 12,13-Dibutyrate ; pharmacology ; Primary Cell Culture ; Protein Kinase C ; metabolism

Hydrogen peroxide (H2O2) and free radicals cause oxidative stress, which induces cellular injuries, metabolic dysfunction, and even cell death in various clinical abnormalities. Fullerene (C60) is critical for scavenging oxygen free radicals originated from cell metabolism, and reduced glutathione (GSH) is another important endogenous antioxidant. In this study, a novel water-soluble reduced glutathione fullerene derivative (C60-GSH) was successfully synthesized, and its beneficial roles in protecting against H2O2-induced oxidative stress and apoptosis in cultured HEK 293T cells were investigated. Fourier Transform infrared spectroscopy and (1)H nuclear magnetic resonance were used to confirm the chemical structure of C60-GSH. Our results demonstrated that C60-GSH prevented the reactive oxygen species (ROS)-mediated cell damage. Additionally, C60-GSH pretreatment significantly attenuated H2O2-induced superoxide dismutase (SOD) consumption and malondialdehyde (MDA) elevation. Furthermore, C60-GSH inhibited intracellular calcium mobilization, and subsequent cell apoptosis via bcl-2/bax-caspase-3 signaling pathway induced by H2O2 stimulation in HEK 293T cells. Importantly, these protective effects of C60-GSH were superior to those of GSH. In conclusion, these results suggested that C60-GSH has potential to protect against H2O2-induced cell apoptosis by scavenging free radicals and maintaining intracellular calcium homeostasis without evident toxicity.
Antioxidants ; pharmacology ; Apoptosis ; drug effects ; Calcium ; metabolism ; Caspase 3 ; genetics ; metabolism ; Cell Survival ; drug effects ; Fullerenes ; chemistry ; pharmacology ; Gene Expression Regulation ; Glutathione ; analogs & derivatives ; pharmacology ; HEK293 Cells ; Humans ; Hydrogen Peroxide ; antagonists & inhibitors ; pharmacology ; Ion Transport ; drug effects ; Malondialdehyde ; antagonists & inhibitors ; metabolism ; Oxidative Stress ; drug effects ; Proto-Oncogene Proteins c-bcl-2 ; genetics ; metabolism ; Reactive Oxygen Species ; antagonists & inhibitors ; metabolism ; Signal Transduction ; Superoxide Dismutase ; metabolism ; bcl-2-Associated X Protein ; genetics ; metabolism

OBJECTIVETo investigate the absorption and transport mechanism of magnolol in Caco-2 cell model.

METHODSA human intestinal epithelial cell model Caco-2 cell in vitro cultured was applied to study the absorption and transport of magnolol, the effects of time, donor concentration, P-gp inhibitor verapamil, pH and temperature on the absorption and transport of magnolol were investigated. The determination of magnolol was performed by high performance liquid chromatography, then the values of apparent permeability coefficient (P app ) and P ratio Basolateral-to-Apical (BL-to-AP)/Apical-to-Basolateral (AP-to-BL) were calculated.

RESULTSIn Caco-2 cell model, comparing the amounts of transport of AP-to-BL and BL-to-AP, the latter was larger. At the same donor concentration, either the amounts of transport of AP-to-BL or BL-to-AP increased with increase in donor concentration and incubation time. Verapamil could significantly improve the amounts of transport of AP-to-BL. The transport of AP-to-BL and BL-to-AP depended on temperature, and there was no significant effect of pH on the transport of AP-to-BL.

CONCLUSIONMagnolol could be transported through the intestinal mucosa via a passive diffusion mechanism primarily, coexisting with a carrier-mediated transport, at the same time, the efflux mechanism could be involved.

Biological Transport ; drug effects ; Biphenyl Compounds ; metabolism ; Caco-2 Cells ; Chromatography, High Pressure Liquid ; Humans ; Hydrogen-Ion Concentration ; drug effects ; Intestinal Absorption ; drug effects ; Lignans ; metabolism ; Models, Biological ; Temperature ; Time Factors ; Verapamil ; pharmacology

OBJECTIVETo investigate the mechanism of Shugan Jianpi Recipe (SJR) on the ion transportation of diarrhea predominant irritable bowel syndrome (IBS-D) colon mucosa induced by 5-HT.

METHODSTotally 36 male SD rats were randomly divided into three groups, i. e., the normal group, the model group, and the SJR group, 12 in each group. IBS-D Rat model was induced by intracolonic instillation of acetic acid and restraint stress. After successful modeling, normal saline was given to rats in the normal group and the model group, while SJR was given to those in the SJR group by gastrogavage for 14 days. The short circuit current (lsc) technology was used to measure 5-HT induced lsc changes of the colon mucosa under the actions of drugs and specific blocking agents.

RESULTSThere was no difference in basal current (BC), the potential difference (PD), and transmembrane resistance (TR) of the distal colon among the 3 groups (all P > 0.05). The 5-HT induced short circuit current change (delta lsc) was lower in the model group than in the normal group (P < 0.05), and it was higher in the SJR group than in the model group (P < 0.05). When 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS, 500 micromol/L), an Ca(+)-dependent Cl- channel blocker, was added from the epiphragm of the colonic mucosa, the 5-HT induced delta lsc was lower in the model group than in the normal group (P < 0.05), and it was higher in the SJR group than in the model group (P < 0.05). When Na+ was substituted in the epiphragm solution (Na+ free) or amiloride (100 micromol/L) was added from the epiphragm of the colonic mucosa, an epithelial Na+ channel blocker, the 5-HT induced delta lsc was lower in the model group than in the normal group (P < 0.05), and it was higher in the SJR group than in the model group (P < 0.05).

CONCLUSIONSSJR could affect the transmembrane electrolyte transportation of IBS-D rat induced by 5-HT through regulating the secretion of Cl- and HCO3-. The effects might be achieved by the coordination of apical Cl- channel CFTR, basolateral Na(+)-K+ ATPase, sodium-potassium-chloride cotransporter, sodium-bicarbonate cotransporter, Cl-/HCO3- exchanger, as well as K+ channel.

Animals ; Colon ; drug effects ; metabolism ; Diarrhea ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Intestinal Mucosa ; drug effects ; metabolism ; Ion Transport ; drug effects ; Irritable Bowel Syndrome ; metabolism ; Male ; Rats ; Rats, Sprague-Dawley

Hyperoxic ventilation induces detrimental effects on the respiratory system, and ambient oxygen may be harmful unless compensated by physiological anti-oxidants, such as vitamin C. Here we investigate the changes in electrolyte transport of airway epithelium in mice exposed to normobaric hyperoxia and in gulonolacton oxidase knock-out (gulo[-/-]) mice without vitamin C (Vit-C) supplementation. Short-circuit current (Isc) of tracheal epithelium was measured using Ussing chamber technique. After confirming amiloride-sensitive Na+ absorption (DeltaIsc,amil), cAMP-dependent Cl- secretion (DeltaIsc,forsk) was induced by forskolin. To evaluate Ca2+-dependent Cl- secretion, ATP was applied to the luminal side (DeltaIsc,ATP). In mice exposed to 98% PO2 for 36 hr, DeltaIsc,forsk decreased, DeltaIsc,amil and DeltaIsc,ATP was not affected. In gulo(-/-) mice, both DeltaIsc,forsk and DeltaIsc,ATP decreased from three weeks after Vit-C deprivation, while both were unchanged with Vit-C supplementation. At the fourth week, tissue resistance and all electrolyte transport activities were decreased. An immunofluorescence study showed that the expression of cystic fibrosis conductance regulator (CFTR) was decreased in gulo(-/-) mice, whereas the expression of KCNQ1 K+ channel was preserved. Taken together, the CFTR-mediated Cl- secretion of airway epithelium is susceptible to oxidative stress, which suggests that supplementation of the antioxidant might be beneficial for the maintenance of airway surface liquid.
Animals ; Ascorbic Acid Deficiency/*metabolism ; Biological Transport/drug effects ; Chlorides/*metabolism ; Cystic Fibrosis Transmembrane Conductance Regulator/antagonists & inhibitors/drug ; Forskolin/pharmacology ; Hyperbaric Oxygenation ; Hyperoxia/*physiopathology ; Ion Transport/drug effects ; Mice ; Mice, Inbred C57BL ; Mice, Inbred ICR ; Mice, Knockout/metabolism ; Mice, Transgenic ; Microscopy, Fluorescence ; Oxidative Stress ; Oxygen/adverse effects/pharmacology ; Potassium Channels/metabolism ; Respiratory Mucosa/drug effects/*metabolism/secretion ; Sodium ; Sugar Acids/metabolism

OBJECTIVETo explore the transmembrane transport and metabolism of diammonium glycyrrhizinate in intestines of rats.

METHODAn Ussing Chamber model were used to investigate the transmembrane transport of diammonium glycyrrhizinate (GZ), the concentrations of diammonium glycyrrhizinate and its two metabolites were determined by HPLC.

RESULTThe permeability coefficients of GZ in difference intestinal mucous membranes were ranged from 0.3 x 10(-6) cm x s(-1) to 1.1 x 10(-6) cm x s(-1). The metabolism of GZ in enterocytes during its transport process was negligible. The concentration of diammonium glycyrrhizinate and pH had limit effects on the transport amount and the permeability coefficients of GZ.

CONCLUSIONGZ is a low permeability drug, but it can be absorbed at all segments of the small intestine in rats. Ileum is the major absorption region of GZ.

Animals ; Biological Transport ; Cell Membrane Permeability ; Glycyrrhizic Acid ; metabolism ; pharmacokinetics ; Hydrogen-Ion Concentration ; Intestine, Small ; chemistry ; drug effects ; metabolism ; Male ; Models, Biological ; Rats ; Rats, Sprague-Dawley

To study the effects of major components of Maijunan tablets, puerarin (Pue) and rhynchophylline (Rhy) on the transport of hydrochlorothiazide (Hct) Caco-2 cell monolayer model, the transport parameters of Hct, such as apparent permeability coefficient (P(app) (B --> A) and P(app) (A --> B)) and the ratio of P(app) (B --> A) versus P(app) (A --> B), were studied and compared when Hct was used solely and co-used with Pue and/or Rhy. The effects of drug concentrations, conveying times, P-glyprotein (P-gp) inhibitor verapamil and conveying Liq pH values on the transport of Hct in the above conditions were also investigated. The results indicated that the absorption of Hct in Caco-2 cell monolayer model could be a carrier-mediated active transport, along with the excretion action mediated by P-gp. Pue can decrease the excretion action of Hct mediated by P-gp, and Rhy had no significant effect on the transport of Hct. The co-use of Hct, Pue and Rhy enhanced the absorption of Hct. Meanwhile, conveying Liq pH value had significant influence on the transport of Hct. The absorption of Hct at pH 6.0 was higher than that at pH 7.4.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; Absorption ; drug effects ; Biological Transport, Active ; drug effects ; Caco-2 Cells ; Drugs, Chinese Herbal ; administration & dosage ; isolation & purification ; pharmacology ; Humans ; Hydrochlorothiazide ; pharmacokinetics ; Hydrogen-Ion Concentration ; Indole Alkaloids ; administration & dosage ; isolation & purification ; pharmacology ; Isoflavones ; administration & dosage ; isolation & purification ; pharmacology ; Plants, Medicinal ; chemistry ; Time Factors ; Vasodilator Agents ; administration & dosage ; isolation & purification ; pharmacology ; Verapamil ; pharmacology

To study the effect of liquiritin (Liq) on the transport of strychnine (Str) in Caco-2 cell monolayer model, the transport parameters of Str, such as apparent permeability coefficient (P app (B-->A) and P app (A-->B)) and cumulative transport amount (TRcum), were determined and comparatively analyzed when Str was used solely and co-used with Liq. The effect of drug concentrations, conveying times, P-glycoprotein (P-gp) inhibitor verapamil and conveying liquor pH values on the transport of Str were also investigated. The results indicated that the absorption of Str in Caco-2 cell monolayer model was well and the passive transference was the main intestinal absorption mechanism of Str in the Caco-2 monolayer model, along with the excretion action mediated by P-gp. Liq enhanced the absorption of Str. Meanwhile, conveying liquor pH value had significant influence on the excretion transport of Str.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; Absorption ; drug effects ; Biological Transport ; drug effects ; Caco-2 Cells ; Flavanones ; isolation & purification ; pharmacology ; Glucosides ; isolation & purification ; pharmacology ; Glycyrrhiza uralensis ; chemistry ; Humans ; Hydrogen-Ion Concentration ; Permeability ; Plants, Medicinal ; chemistry ; Strychnine ; isolation & purification ; pharmacokinetics ; Strychnos nux-vomica ; chemistry ; Verapamil ; pharmacology

This study aimed to investigate the transport characteristics of aripiprazole. A human intestinal epithelial cell model Caco-2 cell in vitro cultured had been applied to study the transport of aripiprazole. The effects of time, concentration of donor solutions, pH, temperature and P-glycoprotein inhibitor on the transport of aripiprazole were investigated. The determination of aripiprazole was performed by HPLC. It is concluded that aripiprazole is transported through the intestinal mucosa via a passive diffusion mechanism primarily, coexisting with a carrier-mediated transport. The transport of aripiprazole is positively correlated to transport time, pH, and temperature. Papp increased with donor concentrations up to 10 microg x mL(-1), and then decreased for higher concentrations. The P-glycoprotein inhibitor cyclosporine A significantly enhanced the transport amount of aripiprazole.
ATP-Binding Cassette, Sub-Family B, Member 1 ; antagonists & inhibitors ; Antipsychotic Agents ; administration & dosage ; pharmacokinetics ; Aripiprazole ; Biological Transport ; drug effects ; Caco-2 Cells ; Cyclosporine ; pharmacology ; Dose-Response Relationship, Drug ; Humans ; Hydrogen-Ion Concentration ; Piperazines ; administration & dosage ; pharmacokinetics ; Quinolones ; administration & dosage ; pharmacokinetics ; Temperature ; Time Factors

Drug resistant bacteria is an increasingly urgent challenge to public health. Bacteria adaptation and extensive abuse of antibiotics contribute to this dilemma. Active efflux of antibiotics is employed by the bacteria to survive the antibiotic pressure. Efflux pump is one of the hot spots of current drug related studies and ideal targets for the improvement of treatment. The efflux pumps and related mechanisms of action, regulation of expression and methodologies were summarized. Comparative genomics analyses were employed to elucidate the underlying mechanisms of action and evolution of efflux pump as exemplified by the Mycobacterium in our lab, which is a crucial re-emerging threat to global public health. The pathway and state-of-art drug development of efflux pump related drugs are included too.
ATP-Binding Cassette Transporters ; antagonists & inhibitors ; drug effects ; physiology ; Anti-Bacterial Agents ; metabolism ; pharmacology ; Bacteria ; metabolism ; Drug Resistance, Multiple, Bacterial ; drug effects ; genetics ; Ion Pumps ; antagonists & inhibitors ; drug effects ; physiology ; Membrane Transport Proteins ; drug effects ; physiology ; Multidrug Resistance-Associated Proteins ; drug effects ; physiology ; Mycobacterium ; metabolism