Greater adenosine A2A receptor densities in cardiac and skeletal muscle in endurance-trained men: a [11C]TMSX PET study

Mizuno, Masaki; Kimura, Yuichi; Tokizawa, Ken; Oda, Kazuhiro; Sasaki, Toru; Nakamura, Yoshio; Muraoka, Isao; Ishiwata, Kiichi

doi:10.1016/j.nucmedbio.2005.07.003

Cited by 38 publications

(33 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…BAT and WAT have not been studied with [ 11 C]TMSX-PET previously, but a study analyzing A2AR density in human muscle tissue [21] reported similar DV values in skeletal muscle as our current study. The analysis of [ 11 C]TMSX PET images has previously required arterial blood sampling for determination of the input function [18, 20, 21].…”

Section: Discussionsupporting

confidence: 79%

“…The analysis of [ 11 C]TMSX PET images has previously required arterial blood sampling for determination of the input function [18, 20, 21]. Arterial cannulation, however, is an invasive procedure which is not always possible or successful, and it requires experienced staff and resources of an anesthesiologist, which may limit the use of the radioligand.…”

Section: Discussionmentioning

confidence: 99%

“…The PET radioligand [ 11 C]TMSX binds specifically to A2AR, providing a tool to study changes in receptor physiology and occupancy. This method has previously been used to study the brain [16–18] and skeletal or cardiac muscle [19–21], but not adipose tissue.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Regulation of human brown adipose tissue by adenosine and A2A receptors – studies with [15O]H2O and [11C]TMSX PET/CT

Lahesmaa

Oikonen

Helin

et al. 2018

Eur J Nucl Med Mol Imaging

View full text Add to dashboard Cite

Adenosine administration caused a maximal perfusion effect in human supraclavicular BAT, indicating increased oxidative metabolism. Cold exposure increased noradrenaline concentrations and decreased the density of A2AR available for radioligand binding in BAT, suggesting augmented release of endogenous adenosine. Our results show that adenosine and A2AR are relevant for activation of human BAT, and A2AR provides a future target for enhancing BAT metabolism.

show abstract

Section: Discussionsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Regulation of human brown adipose tissue by adenosine and A2A receptors – studies with [15O]H2O and [11C]TMSX PET/CT

Lahesmaa

Oikonen

Helin

et al. 2018

Eur J Nucl Med Mol Imaging

View full text Add to dashboard Cite

show abstract

“…The physiological mechanisms responsible for this result are unknown and beyond the scope of this investigation. However, the concentration of adenosine receptors (the presumed primary target of caffeine) do appear to be higher in trained compared to untrained individuals [34]. And though highly speculative, the higher concentration of adenosine receptors may increase tissue sensitivity to any given concentration of adenosine, thereby requiring larger doses of caffeine to elicit a desirable effect.…”

Section: Discussionmentioning

confidence: 99%

Time of Day and Training Status Both Impact the Efficacy of Caffeine for Short Duration Cycling Performance

et al. 2016

View full text Add to dashboard Cite

This project was designed to assess the effects of time of day and training status on the benefits of caffeine supplementation for cycling performance. Twenty male subjects (Age, 25 years; Peak oxygen consumption, 57 mL·kg−1·min−1) were divided into tertiles based on training levels, with top and bottom tertiles designated as ‘trained’ (n = 7) and ‘untrained’ (n = 7). Subjects completed two familiarization trials and four experimental trials consisting of a computer-simulated 3-km cycling time trial (TT). The trials were performed in randomized order for each combination of time of day (morning and evening) and treatment (6mg/kg of caffeine or placebo). Magnitude-based inferences were used to evaluate all treatment effects. For all subjects, caffeine enhanced TT performance in the morning (2.3% ± 1.7%, ‘very likely’) and evening (1.4% ± 1.1%, ‘likely’). Both untrained and trained subjects improved performance with caffeine supplementation in the morning (5.5% ± 4.3%, ‘likely’; 1.0% ± 1.7%, ‘likely’, respectively), but only untrained subjects rode faster in the evening (2.9% ± 2.6%, ‘likely’). Altogether, our observations indicate that trained athletes are more likely to derive ergogenic effects from caffeine in the morning than the evening. Further, untrained individuals appear to receive larger gains from caffeine in the evening than their trained counterparts.

show abstract

“…In a whole body radiation dosimetry study in healthy controls with 120 minutes emission scanning, the highest [ 11 C]TMSX uptake was seen in the liver for the whole period, followed by high uptakes in the heart and kidneys in the early phase and in the gallbladder an urinary bladder in later phase. 31 Since A 2A R densities in the cardiac and skeletal muscles have been reported to be greater in endurance-trained men compared with healthy men, 32 it could be postulated that increasing age and physical disability caused by chronic diseases (such as MS and PD), could cause differences in the biodistribution when compared with healthy controls. However, V T estimates should be independent from the plasma clearance (and thus the biodistribution of the radioligand), because the tissue TAC is estimated in relation to the plasma activity.…”

Section: Roimentioning

confidence: 99%

Automated Reference Region Extraction and Population-Based Input Function for Brain [¹¹C]TMSX PET Image Analyses

Rissanen

Tuisku

Luoto

et al. 2014

J Cereb Blood Flow Metab

View full text Add to dashboard Cite

[ 11 C]TMSX ([7-N-methyl-11 C]-(E)-8-(3,4,5-trimethoxystyryl)-1,3,7-trimethylxanthine) is a selective adenosine A2A receptor (A 2A R) radioligand. In the central nervous system (CNS), A 2A R are linked to dopamine D 2 receptor function in striatum, but they are also important modulators of inflammation. The golden standard for kinetic modeling of brain [ 11 C]TMSX positron emission tomography (PET) is to obtain arterial input function via arterial blood sampling. However, this method is laborious, prone to errors and unpleasant for study subjects. The aim of this work was to evaluate alternative input function acquisition methods for brain [ 11 C] TMSX PET imaging. First, a noninvasive, automated method for the extraction of gray matter reference region using supervised clustering (SCgm) was developed. Second, a method for obtaining a population-based arterial input function (PBIF) was implemented. These methods were created using data from 28 study subjects (7 healthy controls, 12 multiple sclerosis patients, and 9 patients with Parkinson's disease). The results with PBIF correlated well with original plasma input, and the SCgm yielded similar results compared with cerebellum as a reference region. The clustering method for extracting reference region and the population-based approach for acquiring input for dynamic [ 11 C]TMSX brain PET image analyses appear to be feasible and robust methods, that can be applied in patients with CNS pathology.

show abstract

Greater adenosine A2A receptor densities in cardiac and skeletal muscle in endurance-trained men: a [11C]TMSX PET study

Cited by 38 publications

References 28 publications

Regulation of human brown adipose tissue by adenosine and A2A receptors – studies with [15O]H2O and [11C]TMSX PET/CT

Regulation of human brown adipose tissue by adenosine and A2A receptors – studies with [15O]H2O and [11C]TMSX PET/CT

Time of Day and Training Status Both Impact the Efficacy of Caffeine for Short Duration Cycling Performance

Automated Reference Region Extraction and Population-Based Input Function for Brain [¹¹C]TMSX PET Image Analyses

Contact Info

Product

Resources

About

Greater adenosine A2A receptor densities in cardiac and skeletal muscle in endurance-trained men: a [11C]TMSX PET study

Cited by 38 publications

References 28 publications

Regulation of human brown adipose tissue by adenosine and A2A receptors – studies with [15O]H2O and [11C]TMSX PET/CT

Regulation of human brown adipose tissue by adenosine and A2A receptors – studies with [15O]H2O and [11C]TMSX PET/CT

Time of Day and Training Status Both Impact the Efficacy of Caffeine for Short Duration Cycling Performance

Automated Reference Region Extraction and Population-Based Input Function for Brain [11C]TMSX PET Image Analyses

Contact Info

Product

Resources

About

Automated Reference Region Extraction and Population-Based Input Function for Brain [¹¹C]TMSX PET Image Analyses