scholarly journals Head-to-head comparison of (R)-[11C]verapamil and [18F]MC225 in non-human primates, tracers for measuring P-glycoprotein function

2021 ◽  
Author(s):  
Lara García-Varela ◽  
David Vállez García ◽  
Pablo Aguiar ◽  
Takeharu Kakiuchi ◽  
Hiroyuki Ohba ◽  
...  
Keyword(s):  
Regional Differences ◽  
Compartment Model ◽  
Input Function ◽  
Positive Slope ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Tracer Kinetic ◽  
Best Parameter ◽  
Pet Scans

Abstract Purpose P-glycoprotein (P-gp) function is altered in several brain disorders; thus, it is of interest to monitor the P-gp function in vivo using PET. (R)-[11C]verapamil is considered the gold standard tracer to measure the P-gp function; however, it presents some drawbacks that limit its use. New P-gp tracers have been developed with improved properties, such as [18F]MC225. This study compares the characteristics of (R)-[11C]verapamil and [18F]MC225 in the same subjects. Methods Three non-human primates underwent 4 PET scans: 2 with (R)-[11C]verapamil and 2 with [18F]MC225, at baseline and after P-gp inhibition. The 30-min PET data were analyzed using 1-Tissue Compartment Model (1-TCM) and metabolite-corrected plasma as input function. Tracer kinetic parameters at baseline and after inhibition were compared. Regional differences and simplified methods to quantify the P-gp function were also assessed. Results At baseline, [18F]MC225 VT values were higher, and k2 values were lower than those of (R)-[11C]verapamil, whereas K1 values were not significantly different. After inhibition, VT values of the 2 tracers were similar; however, (R)-[11C]verapamil K1 and k2 values were higher than those of [18F]MC225. Significant regional differences between tracers were found at baseline, which disappeared after inhibition. The positive slope of the SUV-TAC was positively correlated to the K1 and VT of both tracers. Conclusion [18F]MC225 and (R)-[11C]verapamil show comparable sensitivity to measure the P-gp function in non-human primates. Moreover, this study highlights the 30-min VT as the best parameter to measure decreases in the P-gp function with both tracers. [18F]MC225 may become the first radiofluorinated tracer able to measure decreases and increases in the P-gp function due to its higher baseline VT.

scholarly journals Head to head comparison of (R)-[11C]verapamil and [18F]MC225 in non-human primates, tracers for measuring P-glycoprotein function

2021 ◽  
Author(s):  
Lara Garcia Varela ◽  
David Vállez García ◽  
Pablo Aguiar ◽  
Teratuka Kakiuchi ◽  
Hiroyuki Ohba ◽  
...  
Keyword(s):  
Regional Differences ◽  
Input Function ◽  
Brain Disorders ◽  
Positive Slope ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Tracer Kinetic ◽  
Best Parameter ◽  
Pet Scans

Abstract Purpose P-glycoprotein (P-gp) function is altered in several brain disorders; thus, it is of interest to monitor the P-gp function in vivo using PET. (R)-[11C]verapamil is considered as the gold standard tracer to measure the P-gp function, however, it presents some drawbacks that limit its use. New P-gp tracers have been developed with improved properties, such as [18F]MC225. This study compares the characteristics of (R)-[11C]verapamil and [18F]MC225 in the same subjects. Methods Three non-human primates underwent 4 PET scans: 2 with (R)-[11C]verapamil and 2 with [18F]MC225, at baseline and after P-gp inhibition. The 30-min PET data were analyzed using 1-TCM and metabolite-corrected-plasma as input function. Tracer kinetic parameters at baseline and after-inhibition were compared. Regional differences and simplified methods to quantify the P-gp function were also assessed. Results At baseline, [18F]MC225 VT values were higher and k2 values were lower than those of (R)-[11C]verapamil, whereas K1 values were not significantly different. After-inhibition, VT values of the 2 tracers were similar, however, (R)-[11C]verapamil K1 and k2 values were higher than those of [18F]MC225. Significant regional differences between tracers were found at baseline, which disappeared after inhibition. The positive slope of the SUV-TAC was positively correlated to the K1 and VT of both tracers. Conclusion [18F]MC225 and (R)-[11C]verapamil show comparable sensitivity to measure the P-gp function in non-human primates. Moreover, this study highlights the 30-min VT as the best parameter to measure decreases in the P-gp function with both tracers. [18F]MC225 may become the first radiofluorinated tracer able to measure decreases and increases in the P-gp function due to its higher baseline VT.

scholarly journals Assessment of Regional Differences in Tariquidar-Induced P-Glycoprotein Modulation at the Human Blood–Brain Barrier

2009 ◽  
Vol 30 (3) ◽  
pp. 510-515 ◽  
Author(s):  
Martin Bauer ◽  
Rudolf Karch ◽  
Friederike Neumann ◽  
Claudia C Wagner ◽  
Kurt Kletter ◽  
...  
Keyword(s):  
Regional Differences ◽  
Statistical Parametric Mapping ◽  
Brain Regions ◽  
Parahippocampal Gyrus ◽  
Glycoprotein P ◽  
P Glycoprotein ◽  
Positron Emission ◽  
Before And After ◽  
Induced Changes ◽  
Pet Scans

We attempted to assess regional differences in cerebral P-glycoprotein (P-gp) function by performing paired positron emission tomography (PET) scans with the P-gp substrate ( R)-[11C]verapamil in five healthy subjects before and after i.v. infusion of tariquidar (2 mg/kg). Comparison of tariquidar-induced changes in distribution volumes ( DVs) in 42 brain regions of interest (ROIs) failed to detect significant differences among brain ROIs. Statistical parametric mapping analysis of parametric DV images visualized symmetrical bilateral clusters with moderately higher DV increases in response to tariquidar administration in cerebellum, parahippocampal gyrus, olfactory gyrus, and middle temporal lobe and cortex, which might reflect moderately decreased P-gp function and expression.

scholarly journals Upregulations of Clcn3 and P-Gp Provoked by Lens Osmotic Expansion in Rat Galactosemic Cataract

2017 ◽  
Vol 2017 ◽  
pp. 1-8
Author(s):  
Lixia Ji ◽  
Lixia Cheng ◽  
Zhihong Yang
Keyword(s):  
Osmotic Stress ◽  
Early Stage ◽  
Lens Epithelial Cells ◽  
Anterior Capsule ◽  
Glycoprotein P ◽  
Protein Levels ◽  
P Glycoprotein ◽  
Sugar Cataract

Objective.Lens osmotic expansion, provoked by overactivated aldose reductase (AR), is the most essential event of sugar cataract. Chloride channel 3 (Clcn3) is a volume-sensitive channel, mainly participating in the regulation of cell fundamental volume, and P-glycoprotein (P-gp) acts as its modulator. We aim to study whether P-gp and Clcn3 are involved in lens osmotic expansion of galactosemic cataract.Methods and Results.In vitro, lens epithelial cells (LECs) were primarily cultured in gradient galactose medium (10–60 mM), more and more vacuoles appeared in LEC cytoplasm, and mRNA and protein levels of AR, P-gp, and Clcn3 were synchronously upregulated along with the increase of galactose concentration. In vivo, we focused on the early stage of rat galactosemic cataract, amount of vacuoles arose from equatorial area and scattered to the whole anterior capsule of lenses from the 3rd day to the 9th day, and mRNA and protein levels of P-gp and Clcn3 reached the peak around the 9th or 12th day.Conclusion. Galactosemia caused the osmotic stress in lenses; it also markedly leads to the upregulations of AR, P-gp, and Clcn3 in LECs, together resulting in obvious osmotic expansion in vitro and in vivo.

scholarly journals Immuno-oncology agent IPI-549 is a modulator of P-glycoprotein (P-gp, MDR1, ABCB1)-mediated multidrug resistance (MDR) in cancer: In vitro and in vivo

2019 ◽  
Vol 442 ◽  
pp. 91-103 ◽  
Author(s):  
Albert A. De Vera ◽  
Pranav Gupta ◽  
Zining Lei ◽  
Dan Liao ◽  
Silpa Narayanan ◽  
...  
Keyword(s):  
Multidrug Resistance ◽  
Glycoprotein P ◽  
P Glycoprotein

Dietary Nucleotide Supplements in Infant Formula Modify the Expression of P-glycoprotein in the Intestinal Epithelium in vitro

2009 ◽  
Vol 79 (56) ◽  
pp. 381-387 ◽  
Author(s):  
Mary Bebawy ◽  
Christine Rasmussen ◽  
Shwetha Sambasivam ◽  
Shisan Bao
Keyword(s):  
Infant Formula ◽  
Dependent Manner ◽  
Drug Bioavailability ◽  
Concentration Dependent Manner ◽  
Glycoprotein P ◽  
Colon Cells ◽  
P Glycoprotein ◽  
Dietary Nucleotides

The effect of dietary nucleotides at concentrations found in supplemented infant formula on P-glycoprotein (P-gp) expression in colon cells was examined. We report that P-gp expression in colon cells was significantly decreased in a time- and concentration-dependent manner. When colon cells were co-cultured with lymphocytes, so as to mimic the involvement of gut-associated lymphoid tissue in normal gut pathophysiology, we observed a reversal of this effect with a demonstrated increase in P-gp expression. These findings have important implications on effects of nucleotide exposure on increasing drug bioavailability, reducing the capacity for xenobiotic efflux, and increasing the risk of inflammatory bowel disease in susceptible infants. Future studies are directed at defining both the mechanisms underlying these findings and effects of dietary nucleotide supplementation in vivo.

scholarly journals Pharmacokinetic Interactions of Herbs with Cytochrome P450 and P-Glycoprotein

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Hyun-Jong Cho ◽  
In-Soo Yoon
Keyword(s):  
Cytochrome P450 ◽  
Glycoprotein P ◽  
Metabolizing Enzymes ◽  
Herbal Products ◽  
P Glycoprotein ◽  
Concurrent Use ◽  
Substrate Drug ◽  
And Function

The concurrent use of drugs and herbal products is becoming increasingly prevalent over the last decade. Several herbal products have been known to modulate cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp) which are recognized as representative drug metabolizing enzymes and drug transporter, respectively. Thus, a summary of knowledge on the modulation of CYP and P-gp by commonly used herbs can provide robust fundamentals for optimizing CYP and/or P-gp substrate drug-based therapy. Herein, we review ten popular medicinal and/or dietary herbs as perpetrators of CYP- and P-gp-mediated pharmacokinetic herb-drug interactions. The main focus is placed on previous works on the ability of herbal extracts and their phytochemicals to modulate the expression and function of CYP and P-gp in severalin vitroandin vivoanimal and human systems.

Assessment of Pharmacokinetic Drug–Drug Interactions in Humans: In Vivo Probe Substrates for Drug Metabolism and Drug Transport Revisited

2019 ◽  
Vol 59 (1) ◽  
pp. 507-536 ◽  
Author(s):  
Uwe Fuhr ◽  
Chih-hsuan Hsin ◽  
Xia Li ◽  
Wafaâ Jabrane ◽  
Fritz Sörgel
Keyword(s):  
Drug Transport ◽  
Quantitative Prediction ◽  
Pharmacokinetic Parameters ◽  
Glycoprotein P ◽  
Therapeutic Drugs ◽  
P Glycoprotein ◽  
Clinical Drug ◽  
Pharmacokinetic Drug

Pharmacokinetic parameters of selective probe substrates are used to quantify the activity of an individual pharmacokinetic process (PKP) and the effect of perpetrator drugs thereon in clinical drug–drug interaction (DDI) studies. For instance, oral caffeine is used to quantify hepatic CYP1A2 activity, and oral dagibatran etexilate for intestinal P-glycoprotein (P-gp) activity. However, no probe substrate depends exclusively on the PKP it is meant to quantify. Lack of selectivity for a given enzyme/transporter and expression of the respective enzyme/transporter at several sites in the human body are the main challenges. Thus, a detailed understanding of the role of individual PKPs for the pharmacokinetics of any probe substrate is essential to allocate the effect of a perpetrator drug to a specific PKP; this is a prerequisite for reliably informed pharmacokinetic models that will allow for the quantitative prediction of perpetrator effects on therapeutic drugs, also in respective patient populations not included in DDI studies.

scholarly journals Intestinal P-glycoprotein Expression is Multimodally Regulated by Intestinal Ischemia-Reperfusion

2014 ◽  
Vol 17 (2) ◽  
pp. 266 ◽  
Author(s):  
Yusuke Terada ◽  
Jiro Ogura ◽  
Takashi Tsujimoto ◽  
Kaori Kuwayama ◽  
Takahiro Koizumi ◽  
...  
Keyword(s):  
Intestinal Ischemia ◽  
Ischemia Reperfusion ◽  
Tacrolimus Concentration ◽  
Glycoprotein P ◽  
In Vivo Experiments ◽  
P Glycoprotein ◽  
Blood Tacrolimus Concentration ◽  
Intestinal Ischemia Reperfusion

Purpose. Reactive oxygen species (ROS) have multiple physiological effects that are amount-dependent. ROS are one of the causes of intestinal ischemia-reperfusion (I/R) injury. In this study, we investigated whether the amount of ROS and the degree of intestinal I/R injury affect the expression level of P-glycoprotein (P-gp). Methods. We used hydrogen peroxide (H2O2) as ROS in in vitro experiments. Intestinal I/R model rats, which were subjected 15-min ischemia (I/R-15), were used in in vivo experiments. Results. P-gp expression in Caco-2 cells was increased in response to 1 µM of H2O2 but decreased upon exposure to 10 mM of H2O2. We previously reported that P-gp expression is decreased after intestinal I/R with 30-min ischemia (I/R-30), which time a large amount of ROS is generated. I/R-15 induced slightly less mucosal and oxidative injury than did I/R-30. P-gp expression in the jejunum was increased at 1 h after I/R-15, and ileal paracellular permeability was increased. The blood concentration of tacrolimus, a P-gp substrate, was lower during 0-20 min but was higher during 40-90 min post-administration compared with that in the sham-operated rats. P-gp expression in the ileum was decreased at 6 h after I/R-15, due to abnormal localization of P-gp, resulting in a high blood tacrolimus concentration in rats reperfused for 6 h. Conclusions. ROS multimodally regulate P-gp expression depending on its amount. This is important for understanding the pattern of P-gp expression after intestinal I/R. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

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