Canine digoxin

The ATP-binding cassette transporter P-glycoprotein (P-gp) limits the oral bioavailability of many drugs. Although P-gp has been well studied in humans and mice, little is known about the substrate specificities of many of its species orthologs. To address this, we performed in vitro analysis of P-gp transporter function using HEK293 cells stably expressing human, ovine, porcine, canine, and feline P-gp. We also employed a human physiologically based pharmacokinetic (PBPK) model to assess variations in digoxin exposure resulting from altered P-gp function...

Black ginger is used as an herbal medicine for self-care and health promotion. Black ginger extract has been shown to alter the function of transporters in several cell types. This study demonstrates the interaction between the extract and 5,7-dimethoxyflavone (DMF) on drug efflux mediated by breast cancer resistance proteins (BCRP) and P-glycoprotein (P-gp) in Caco-2 cells and heterologous cell systems [Madin-Darby canine kidney type II (MDCKII) stably transfected with human BCRP (MDCKII/BCRP) or human P-gp (MDCKII/P-gp)]...

BACKGROUND: Endothelial cell-specific molecule-1 (ESM-1) has emerged as a potential biomarker for cardiovascular disease in humans. Myxomatous mitral valve disease (MMVD) is the most common heart disease in dogs, and we hypothesized that MMVD causes chronic inflammation that increases susceptibility to endothelial glycocalyx (eGCX) damage. In this study, we measured the concentration of ESM-1 in a group of dogs with MMVD and evaluated factors affecting eGCX damage. RESULTS: Sixty-four dogs (control, n = 6; MMVD, n = 58) were enrolled in this study...

Targeted osmotic lysis (TOL) is a novel technology that involves the concomitant stimulation of voltage-gated sodium channels (VGSCs) and pharmacological blockade of Na+, K+-ATPase (sodium pumps) causing selective osmotic lysis of highly malignant cancer cells that may offer an option for treating advanced carcinomas in companion animals. We hypothesized, that as in experimental animals, TOL would be able to increase survival beyond that anticipated for animals with advance carcinoma without adversely affecting quality of life...

Pharmaceutical excipients are no longer considered inert and have been shown to influence the activity of metabolic enzymes and transporters, resulting in altered pharmacokinetics of substrate drugs. In this study, the effect of 25 excipients commonly used in drug formulations were investigated for their effect on P-glycoprotein (P-gp) activity. The effect of excipients on P-gp were assessed by measuring the change in the cellular accumulation of a P-gp substrate, digoxin, in MDCK-MDR1 (Madin Darby canine kidney transfected with multidrug resistance 1 gene) cells...

Recently, we transfected the porcine intestinal cell line IPEC-J2, with human P-glycoprotein (P-gp, ABCB1). The resulting cell line, iP-gp, has a high expression of functional human P-gp in the apical membrane, and a low expression of nonhuman ATP-binding cassette (ABC) transporters. The aim of the present work was to investigate the usability of iP-gp cell line for determining transepithelial transport kinetics of the prototypical P-gp substrates digoxin and rhodamine 123. The cell line generated tight monolayers after 16days of culture, reflected by high transepithelial electrical resistance values (TEER>15,000Ω·cm2 ), immunocytochemistry and low fluxes of the paracellular flux marker [14 C]-mannitol...

Madin-Darby canine kidney II cells transfected with one or several transport proteins are commonly used models to study drug transport. In these cells, however, endogenous transporters such as canine Mdr1/P-glycoprotein (Abcb1) complicate the interpretation of transport studies. The aim of this investigation was to establish a Madin-Darby canine kidney II cell line using CRISPR-Cas9 gene-editing technology to knock out endogenous canine Mdr1 (cMdr1) expression. CRISPR-Cas9-mediated Abcb1 homozygous disruption occurred at frequencies of around 20% and resulted in several genotypes...

PURPOSE: Screening interactions of a resolvin E1 analog (RX-10045) with efflux transporters (P-glycoprotein [P-gp], multidrug resistance-associated protein [MRP2], and breast cancer-resistant protein [BCRP]). METHODS: Madin-Darby canine kidney cells transfected with P-gp, MRP2, and BCRP genes were selected for this study. [3H]-Digoxin, [3H]-vinblastine and [3H]-abacavir were selected as model substrates for P-gp, MRP2, and BCRP. Uptake and permeability studies across cell monolayer in both apical to basal (AP-BL) and BL-AP of these substrates were conducted in the presence of specific efflux pump inhibitors and RX-10045...

OBJECTIVE: To identify biomarkers of P-glycoprotein (P-gp) substrate neurotoxicity in transgenic mice expressing the mutant canine ABCB1 gene (ABCB1-1Δ). ANIMALS: 8 ABCB1 knock-in and knock-out transgenic mice expressing the ABCB1-1Δ gene and 8 control mice expressing the wild-type canine ABCB1 gene (ABCB1-WT). PROCEDURES: Groups including 2 ABCB1-1Δ mutant mice and 2 ABCB1-WT mice were administered the P-gp substrates ivermectin (10 mg/kg, SC), doramectin (10 mg/kg, SC), moxidectin (10 mg/kg, PO), or digoxin (1...

BACKGROUND: Eprosartan is an angiotensin II receptor antagonist, used in the treatment of hypertension and heart failure in clinical patients. The objective of this study was to clarify the mechanism underlying hepatic uptake and biliary excretion of eprosartan in rats and humans. METHODS: Perfused rat liver in situ, rat liver slices, isolated rat hepatocytes and human organic anion-transporting polypeptide (OATP)-transfected cells in vitro were used in this study...

Madin-Darby canine kidney (MDCK) cells transfected with human MDR1 gene (MDCK-MDR1) encoding for P-glycoprotein (hPgp, ABCB1) are widely used for transport studies to identify drug candidates as substrates of this efflux protein. Therefore, it is necessary to rely on constant and comparable expression levels of Pgp to avoid false negative or positive results. We generated a cell line with homogenously high and stable expression of hPgp through sorting single clones from a MDCK-MDR1 cell pool using fluorescence-activated cell sorting (FACS)...

The study objectives were 1) to test the hypothesis that the lack of P-glycoprotein (P-gp) and the inhibition of breast cancer resistance protein (Bcrp) at the blood-brain barrier after cassette dosing of potent P-gp and Bcrp inhibitors were due to low plasma concentrations of those inhibitors and 2) to examine the effects of P-gp on the unbound brain (C(u,brain)) and cerebrospinal fluid (CSF) concentrations (C(u,CSF)) of P-gp substrates in rats. In vitro inhibition of 11 compounds (amprenavir, citalopram, digoxin, elacridar, imatinib, Ko143 [(3S,6S,12aS)-1,2,3,4,6,7,12,12a-octahydro-9-methoxy-6-(2-methylpropyl)-1,4-dioxopyrazino[1',2':1,6]pyrido[3,4-b]indole-3-propanoic acid 1,1-dimethylethyl ester], loperamide, prazosin, quinidine, sulfasalazine, and verapamil) on P-gp and Bcrp was examined in P-gp- and Bcrp-expressing Madin-Darby canine kidney cells, respectively...

BACKGROUND: Increased stellate ganglion nerve activity (SGNA) directly precedes the onset of spontaneous atrial tachyarrhythmias (AT) in ambulatory dogs. However, it is difficult to use SGNA for risk stratification and arrhythmia prediction because access to the stellate ganglion requires open chest surgery. Because subcutaneous sympathetic nerve fibers originate from ipsilateral stellate ganglion, we hypothesize that subcutaneous nerve activity (SCNA) can be used as a surrogate of SGNA to predict the immediate onset of AT in ambulatory dogs...

We have reported that the P-gp substrate digoxin required basolateral and apical uptake transport in excess of that allowed by digoxin passive permeability (as measured in the presence of GF120918) to achieve the observed efflux kinetics across MDCK-MDR1-NKI (The Netherlands Cancer Institute) confluent cell monolayers. That is, GF120918 inhibitable uptake transport was kinetically required. Therefore, IC50 measurements using digoxin as a probe substrate in this cell line could be due to inhibition of P-gp, of digoxin uptake transport, or both...

The impact of P-glycoprotein (MDR1, ABCB1) on drug disposition in the lungs as well as its presence and activity in in vitro respiratory drug absorption models remain controversial to date. Hence, we characterised MDR1 expression and the bidirectional transport of the common MDR1 probe (3)H-digoxin in air-liquid interfaced (ALI) layers of normal human bronchial epithelial (NHBE) cells and of the Calu-3 bronchial epithelial cell line at different passage numbers. Madin-Darby Canine Kidney (MDCKII) cells transfected with the human MDR1 were used as positive controls...

Axitinib is an inhibitor of tyrosine kinase vascular endothelin growth factor receptors 1, 2, and 3. The ATP-binding cassette (ABC) and solute carrier (SLC) transport properties of axitinib were determined in selected cellular systems. Axitinib exhibited high passive permeability in all cell lines evaluated (Papp ≥ 6 × 10(-6) cm/s). Active efflux was observed in Caco-2 cells, and further evaluation in multidrug resistance gene 1 (MDR1) or breast cancer resistance protein (BCRP) transfected Madin-Darby canine kidney cells type 2 (MDCK) cells indicated that axitinib is at most only a weak substrate for P-glycoprotein (P-gp) but not BCRP...

P-glycoprotein (P-gp) mediated efflux is recognised to alter the absorption and disposition of a diverse range of substrates. Despite evidence showing the presence of P-gp within the lung, relatively little is known about the transporter's effect upon the absorption and distribution of drugs delivered via the pulmonary route. Here, we present data from an intact isolated rat lung model, alongside two isolated mouse lung models using either chemical or genetic inhibition of P-gp. Data from all three models show inhibition of P-gp increases the extent of absorption of a subset of P-gp substrates (e...

A P-glycoprotein (P-gp) IC₅₀ working group was established with 23 participating pharmaceutical and contract research laboratories and one academic institution to assess interlaboratory variability in P-gp IC₅₀ determinations. Each laboratory followed its in-house protocol to determine in vitro IC₅₀ values for 16 inhibitors using four different test systems: human colon adenocarcinoma cells (Caco-2; eleven laboratories), Madin-Darby canine kidney cells transfected with MDR1 cDNA (MDCKII-MDR1; six laboratories), and Lilly Laboratories Cells--Porcine Kidney Nr...

Transepithelial potential (TEP) is the voltage across a polarized epithelium. In epithelia that have active transport functions, the force for transmembrane flux of an ion is dictated by the electrochemical gradient in which TEP plays an essential role. In epithelial injury, disruption of the epithelial barrier collapses the TEP at the wound edge, resulting in the establishment of an endogenous wound electric field (∼100 mV/mm) that is directed towards the center of the wound. This endogenous electric field is implicated to enhance wound healing by guiding cell migration...

The objective of this study was to clarify the mechanism underlying hepatic uptake of dioscin (diosgenyl 2,4-di-O-a-L-rhamnopyranosyl-p-D-glucopyranoside), an herbal ingredient with antihepatitis activity, in rats and humans. The liver uptake index (LUI) in vivo, perfused rat liver in situ, rat liver slices, isolated rat hepatocytes, and human organic anion-transporting polypeptide (OATP)-transfected cells in vitro were used to evaluate hepatic uptake of dioscin. Values of 11.9% ± 1.6% and 15.0% ± 0.9% of dose for uptake of dioscin were observed by LUI in vivo and perfused rat livers in situ, respectively...