scholarly journals Expression and Localization of P-glycoprotein in Human Heart

2002 ◽  
Vol 50 (10) ◽  
pp. 1351-1356 ◽  
Author(s):  
Konrad Meissner ◽  
Bernhard Sperker ◽  
Christiane Karsten ◽  
Henriette Meyer zu Schwabedissen ◽  
Ute Seeland ◽  
...  
Keyword(s):  
Dilated Cardiomyopathy ◽  
Human Heart ◽  
Cardiac Glycosides ◽  
Transport Proteins ◽  
Rt Pcr ◽  
Glycoprotein P ◽  
Variable Expression ◽  
P Glycoprotein ◽  
The Individual

ABC-type transport proteins, such as P-glycoprotein (P-gp), modify intracellular concentrations of many substrate compounds. They serve as functional barriers against entry of xenobiotics (e.g., in the gut or the blood-brain barrier) or contribute to drug excretion. Expression of transport proteins in the heart could be an important factor modifying cardiac concentrations of drugs known to be transported by P-gp (e.g., β-blockers, cardiac glycosides, doxorubicin). We therefore investigated the expression and localization of P-gp in human heart. Samples from 15 human hearts (left ventricle; five non-failing, five dilated cardiomyopathy, and five ischemic cardiomyopathy) were analyzed for expression of P-gp using real-time RT-PCR, immunohistochemistry, and in situ hybridization. Immunohistochemistry revealed expression of P-gp in endothelium of both arterioles and capillaries of all heart samples. Although P-gp mRNA was detected in all samples, its expression level was significantly reduced in patients with dilated cardiomyopathy. We describe variable expression of P-gp in human heart and its localization in the endothelial wall. Thus, intracardiac concentrations of various compounds may be modified, depending on the individual P-gp level.

scholarly journals Overexpression of P-glycoprotein, MRP2, and CYP3A4 impairs intestinal absorption of octreotide in rats with portal hypertension

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Xiaoyu Sun ◽  
Shunxiong Tang ◽  
Binbin Hou ◽  
Zhijun Duan ◽  
Zhen Liu ◽  
...  
Keyword(s):  
Liver Cirrhosis ◽  
Portal Hypertension ◽  
Western Blot ◽  
In Vitro Experiments ◽  
Rt Pcr ◽  
P Glycoprotein ◽  
Intestinal Microsomes ◽  
First Pass

Abstract Background Portal hypertension (PH) is the main cause of complications and death in liver cirrhosis. The effect of oral administration of octreotide (OCT), a drug that reduces PH by the constriction of mesenteric arteries, is limited by a remarkable intestinal first-pass elimination. Methods The bile duct ligation (BDL) was used in rats to induce liver cirrhosis with PH to examine the kinetics and molecular factors such as P-glycoprotein (P-gp), multidrug resistance-associated protein 2 (MRP2) and cytochrome P450 3A4 (CYP3A4) influencing the intestinal OCT absorption via in situ and in vitro experiments on jejunal segments, transportation experiments on Caco-2 cells and experiments using intestinal microsomes and recombinant human CYP3A4. Moreover, RT-PCR, western blot, and immunohistochemistry were performed. Results Both in situ and in vitro experiments in jejunal segments showed that intestinal OCT absorption in both control and PH rats was largely controlled by P-gp and, to a lesser extent, by MRP2. OCT transport mediated by P-gp and MRP2 was demonstrated on Caco-2 cells. The results of RT-PCR, western blot, and immunohistochemistry suggested that impaired OCT absorption in PH was in part due to the jejunal upregulation of these two transporters. The use of intestinal microsomes and recombinant human CYP3A4 revealed that CYP3A4 metabolized OCT, and its upregulation in PH likely contributed to impaired drug absorption. Conclusions Inhibition of P-gp, MRP2, and CYP3A4 might represent a valid option for decreasing intestinal first-pass effects on orally administered OCT, thereby increasing its bioavailability to alleviate PH in patients with cirrhosis.

scholarly journals Inhibitory Effect of Berberine on Broiler P-glycoprotein Expression and Function: In Situ and In Vitro Studies

2019 ◽  
Vol 20 (8) ◽  
pp. 1966 ◽  
Author(s):  
Yujuan Zhang ◽  
Li Guo ◽  
Jinhu Huang ◽  
Yong Sun ◽  
Fang He ◽  
...  
Keyword(s):  
Molecular Docking ◽  
Inhibitory Effect ◽  
In Vitro Models ◽  
Apparent Permeability ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
And Function ◽  
Xenobiotic Receptor

Overcoming P-glycoprotein (P-gp) efflux is a strategy to improve the absorption and pharmacokinetics of its substrate drugs. Berberine inhibits P-gp and thereby increases the bioavailability of the P-gp substrate digoxin in rodents. However, the effects of berberine on P-gp in chickens are still unclear. Here, we studied the role of berberine in modulating broilers P-gp expression and function through both in situ and in vitro models. In addition, molecular docking was applied to analyze the interactions of berberine with P-gp as well as with chicken xenobiotic receptor (CXR). The results showed that the mRNA expression levels of chicken P-gp and CXR decreased in the ileum following exposure to berberine. The absorption rate constant of rhodamine 123 increased after berberine treatment, as detected using an in situ single-pass intestinal perfusion model. Efflux ratios of P-gp substrates (tilmicosin, ciprofloxacin, clindamycin, ampicillin, and enrofloxacin) decreased and the apparent permeability coefficients increased after co-incubation with berberine in MDCK-chAbcb1 cell models. Bidirectional assay results showed that berberine could be transported by chicken P-gp with a transport ratio of 4.20, and this was attenuated by verapamil (an inhibitor of P-gp), which resulted in a ratio of 1.13. Molecular docking revealed that berberine could form favorable interactions with the binding pockets of both CXR and P-gp, with docking scores of −7.8 and −9.5 kcal/mol, respectively. These results indicate that berberine is a substrate of chicken P-gp and down-regulates P-gp expression in chicken tissues, thereby increasing the absorption of P-gp substrates. Our findings suggest that berberine increases the bioavailability of other drugs and that drug-drug interactions should be considered when it is co-administered with other P-gp substrates with narrow therapeutic windows.

scholarly journals A study of intestinal absorption of bicyclol in rats: active efflux transport and metabolism as causes of its poor bioavailability

2008 ◽  
Vol 11 (3) ◽  
pp. 97 ◽  
Author(s):  
Wei Tan ◽  
Hui Chen ◽  
Jinping Hu ◽  
Yan Li
Keyword(s):  
Cell Monolayer ◽  
Intestinal Perfusion ◽  
Efflux Transport ◽  
Glycoprotein P ◽  
Active Efflux ◽  
The Poor ◽  
P Glycoprotein ◽  
Respective Contribution ◽  
Monolayer Model

Purpose.To determine the possible mechanism of poor bioavailability of bicyclol, and clarify the respective contribution of P- glycoprotein (P-gp) and Cytochrome 3A (CYP3A). Methods. Rat in situ single-pass intestinal perfusion and Caco-2 cell monolayer model with selective inhibitors of CYP3A and P-gp were employed. Results. In rat intestinal perfusion, bicyclol (50µM) appearance in mesenteric blood (Pblood) was increased 3, 12, 16-fold by addition of inhibitors of P-gp (LSN335984), CYP3A ( troleandomycin, TAO) or P-gp and CYP3A (Cyclosporin A, CsA), respectively, whereas permeability of midazolam (CYP3A substrate only) was unchanged by LSN335984 and increased 5 and 1-fold by TAO and CsA. In addition, the metabolized fraction of bicyclol was decreased by 9%, 33%, 36% with inhibitor of P-gp, CYP3A, or P-gp and CYP3A. Moreover, the cumulative amount of bicyclol in mesenteric blood was increased at concentration range 10-100µM of bicyclol in perfusate. The ER (Pappba/Pappab) value of bicyclol in Caco-2 monolayer was significantly deceased by LSN335984 and CsA. Conclusion. The poor bioavailability of bicyclol was mostly due to the P-gp mediated efflux and metabolism by CYP3A in intestine, while CYP3A was believed to make more contribution than P-gp.

scholarly journals Sodium Pump Isoforms in Xenotransplantation: Importance of Biochemical Compatibility

2000 ◽  
Vol 46 (2) ◽  
pp. 234-241 ◽  
Author(s):  
Andrea M Rose ◽  
Hassan M Qazzaz ◽  
Nina Zolotarjova ◽  
Brenda J Mellett ◽  
Alvin W Martin ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Human Heart ◽  
Cardiac Glycosides ◽  
Sodium Pump ◽  
Inhibition Assay ◽  
Α Subunit ◽  
Cardiac Tissues ◽  
Porcine Heart ◽  
The Individual ◽  
Selection Of

Abstract Background: Xenotransplantation of pig hearts to humans could be hampered by the reportedly reduced affinity for digoxin of pig heart. We examined the hypothesis that expression of the individual α-subunit isoforms of the sodium pump [Na+,K+-ATPase (NKA)], the receptor for the plant-derived cardiac glycosides, may be responsible for this difference. Methods: We used a NKA-inhibition assay in combination with Western analysis, immunohistochemistry, and phosphorylation of the NKA α subunit to identify the distribution and expression of α isoforms in four chambers of porcine and human hearts. Results: We confirmed that tissue from porcine heart is less sensitive to digitalis (IC50 = 1740 nmol/L) when compared with human heart (IC50 = 840 nmol/L), whereas porcine cerebral cortex-mix had an affinity comparable to that of human heart (IC50 = 910 nmol/L). Our data show that porcine cerebral cortex-mix and human heart contain all three α isoforms, whereas porcine heart expresses only the α1 isoform. Conclusions: The different expressions of sodium pump isoforms in human vs porcine cardiac tissues suggests that porcine hearts may not be pharmacologically or endocrinologically compatible when used in humans. Studies of both pharmacologic and endocrinologic tissue compatibility are needed prior to selection of organs for xenotransplantation.

Abstract P155: HSF-1 Deletion Induces MDR1 Gene in the Heart and Protects from Doxorubicin-Induced Cardiotoxicity

2011 ◽  
Vol 109 (suppl_1) ◽  
Author(s):  
Karthikeyan Krishnamurthy ◽  
Lawrence Druhan ◽  
Govindasamy Ilangovan
Keyword(s):  
Cardiac Dysfunction ◽  
Mdr1 Gene ◽  
Heat Shock Factor 1 ◽  
Wild Type ◽  
Rt Pcr ◽  
Glycoprotein P ◽  
Knock Out ◽  
P Glycoprotein ◽  
Mdr1 Gene Expression ◽  
Knock Out Mouse

Heat shock factor 1 (HSF-1) has been found to be a frontline responder of different stresses in eukaryotic cells. Deletion of HSF-1 has been reported to develop defects in mice. In the present work we report that deletion of HSF-1 induced multidrug resistance 1 (MDR1) gene and P-glycoprotein (P-gp) expression. Both RT-PCR and western blotting, confirmed the higher level of MDR1 gene expression and P-gp protein in HSF-1 knock out mouse hearts. P-gp is well known ATP binding cassette, which extrudes intracellular drugs upon binding ATP. Hence the phenotype of the P-gp pump in HSF-1 −/− mice was studied in the form of Doxorubicin (Dox) extrusion in the heart. Cardiomyocytes isolated from HSF-1 −/− and HSF-1 +/− mice retained very less intracellular Dox, compared to wild type counterparts. Similarly, both HSF-1 +/− and HSF-1 −/− mice were less susceptible for Dox-induced cardiotoxicity, as seen from reduced cardiac dysfunction in these group against Dox (as confirmed by cardiac MRI and echocardiography). Further confirmatory studies revealed that deletion of HSF-1 enhances NF-B, which subsequently induces MDR1 gene. These results reveal that inactivation of HSF-1 in the heart will be a potential approach to prevent Dox-induced cardiotoxicity.

scholarly journals Investigation of the Functional Role of P-Glycoprotein in Limiting the Oral Bioavailability of Lumefantrine

2013 ◽  
Vol 58 (1) ◽  
pp. 489-494 ◽  
Author(s):  
Wahajuddin ◽  
Kanumuri S. R. Raju ◽  
Sheelendra P. Singh ◽  
Isha Taneja
Keyword(s):  
Intestinal Absorption ◽  
Oral Absorption ◽  
Stability Study ◽  
Cytochrome P450 3A ◽  
Glycoprotein P ◽  
Active Efflux ◽  
P Glycoprotein

ABSTRACTIn the quest to explore the reason for the low and variable bioavailability of lumefantrine, we investigated the possible role of P-glycoprotein (P-gp) in lumefantrine intestinal absorption. Anin situsingle-pass intestinal perfusion study in rats with the P-gp inhibitor verapamil or quinidine and an ATPase assay with human P-gp membranes indicated that lumefantrine is a substrate of P-gp which limits its intestinal absorption. To confirm these findings, anin vivopharmacokinetic study was performed in rats. The oral administration of verapamil (10 mg/kg of body weight) along with lumefantrine caused a significant increase in its bioavailability with a concomitant decrease in clearance. The increase in bioavailability of lumefantrine could be due to inhibition of P-gp and/or cytochrome P450 3A in the intestine/liver by verapamil. However, in a rat intestinal microsomal stability study, lumefantrine was found to be resistant to oxidative metabolism. Further, anin situpermeation study clearly showed a significant role of P-gp in limiting the oral absorption of lumefantrine. Thus, the increase in lumefantrine bioavailability with verapamil is attributed in part to the P-gp-inhibitory ability of verapamil. In conclusion, lumefantrine is a substrate of P-gp, and active efflux by P-gp across the intestine partly contributed to the low/variable bioavailability of lumefantrine.

scholarly journals Expression of P-Glycoprotein in Human Cerebral Cortex Microvessels

2002 ◽  
Vol 50 (12) ◽  
pp. 1671-1676 ◽  
Author(s):  
Daniela Virgintino ◽  
David Robertson ◽  
Mariella Errede ◽  
Vincenzo Benagiano ◽  
Francesco Girolamo ◽  
...  
Keyword(s):  
Cerebral Cortex ◽  
Normal Component ◽  
Transport Systems ◽  
Human Cerebral Cortex ◽  
Functional Protein ◽  
Glycoprotein P ◽  
Caveolin 1 ◽  
Cellular Expression ◽  
P Glycoprotein

P-Glycoprotein (P-gp) is an ATP-dependent efflux transporter that extrudes non-polar molecules, including cytotoxic substances and drugs, from the cells. It was initially found in cancer cells and then was shown to be a normal component of complex transport systems working at the blood-brain barrier (BBB). Previous studies have demonstrated that, in the brain, P-gp is localized on the luminal plasmalemma of BBB endothelial cells and that it may interact with the caveolar compartment of these cells. The aim of this study was to identify the site of cellular expression of P-gp in human brain in situ and to morphologically determine whether an association may exist between P-gp and caveolin-1, a structural and functional protein of the caveolar frame. The study was carried out on human cerebral cortex by immunoconfocal microscopy with antibodies to both P-gp and caveolin-1. The results show that P-gp marks the microvessels of the cortex and that the transporter is localized in the luminal endothelial compartment, where it co-localizes with caveolin-1. The demonstration of this co-localization of P-gp with caveolin-1 contributes a morphological backing to biochemical studies on P-gp/caveolin-1 relationships and leads us to suggest that interactions between these molecules may occur at the BBB endothelia.

scholarly journals Methotrexate Combined with 4-Hydroperoxycyclophosphamide Downregulates Multidrug-Resistance P-Glycoprotein Expression Induced by Methotrexate in Rheumatoid Arthritis Fibroblast-Like Synoviocytes via the JAK2/STAT3 Pathway

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Kaili Qin ◽  
Kailin Chen ◽  
Wenpeng Zhao ◽  
Xiangcong Zhao ◽  
Jing Luo ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Multidrug Resistance ◽  
Mrna Levels ◽  
Proliferation Inhibition ◽  
Rt Pcr ◽  
Glycoprotein P ◽  
Stat3 Pathway ◽  
P Glycoprotein ◽  
Stat3 Phosphorylation ◽  
Fibroblast Like Synoviocytes

Objective. Rheumatoid arthritis (RA) multidrug resistance is associated with P-glycoprotein (P-gp) overexpression. We investigated the effects of methotrexate (MTX) alone and combined with 4-hydroperoxycyclophosphamide (4-HC) on P-gp expression in fibroblast-like synoviocytes (FLSs) from patients with RA and examined the signaling pathway involved. Methods. RA-FLSs were treated with MTX, MTX + 4-HC, AG490 + MTX, or AG490 + MTX + 4-HC for 72 h. Proliferation inhibition rates were determined by MTT assay; P-gp expression was measured by flow cytometry and real-time polymerase chain reaction (RT-PCR); JAK2 and STAT3 were measured by RT-PCR and cell-based ELISA to assess STAT3 signaling. Results. MTX alone significantly induced P-gp expression and mRNA production in RA-FLSs. P-gp expression and mRNA levels were lower in the MTX + 4-HC group than in the MTX-alone group. In contrast to MTX, MTX + 4-HC reduced the STAT3 phosphorylation and downregulated JAK2 and STAT3 mRNA production. Inhibition of constitutively active STAT3 accompanied by 4-HC suppressed P-gp levels in RA-FLSs. The MTT assays revealed no significant differences in proliferation inhibition rates among groups. Conclusions. The increased anti-P-gp effect of MTX + 4-HC versus MTX alone in RA-FLSs was mediated via inhibition of the JAK2/STAT3 pathway and may have helped reverse MDR in refractory RA patients with high-P-gp levels.

Detection of Nucleic Acids in Cells or Tissue Sections Using In situ Polymerase Chain Reaction (PCR)

1996 ◽  
Vol 54 ◽  
pp. 16-17
Author(s):  
J. R. Hully ◽  
K. R. Luehrsen ◽  
K. Aoyagi ◽  
C. Shoemaker ◽  
R. Abramson
Keyword(s):  
Nucleic Acids ◽  
Viral Infections ◽  
Anatomical Location ◽  
Rt Pcr ◽  
Reverse Transcription Pcr ◽  
Cellular Source ◽  
Gene Transcripts ◽  
Initial Description ◽  
In Cells

The development of PCR technology has greatly accelerated medical research at the genetic and molecular levels. Until recently, the inherent sensitivity of this technique has been limited to isolated preparations of nucleic acids which lack or at best have limited morphological information. With the obvious exception of cell lines, traditional PCR or reverse transcription-PCR (RT-PCR) cannot identify the cellular source of the amplified product. In contrast, in situ hybridization (ISH) by definition, defines the anatomical location of a gene and/or it’s product. However, this technique lacks the sensitivity of PCR and cannot routinely detect less than 10 to 20 copies per cell. Consequently, the localization of rare transcripts, latent viral infections, foreign or altered genes cannot be identified by this technique. In situ PCR or in situ RT-PCR is a combination of the two techniques, exploiting the sensitivity of PCR and the anatomical definition provided by ISH. Since it’s initial description considerable advances have been made in the application of in situ PCR, improvements in protocols, and the development of hardware dedicated to in situ PCR using conventional microscope slides. Our understanding of the importance of viral latency or viral burden in regards to HIV, HPV, and KSHV infections has benefited from this technique, enabling detection of single viral copies in cells or tissue otherwise thought to be normal. Clearly, this technique will be useful tool in pathobiology especially carcinogenesis, gene therapy and manipulations, the study of rare gene transcripts, and forensics.

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