Nuklearmedizin 2023; 62(02): 89
DOI: 10.1055/s-0043-1766157
Abstracts | NuklearMedizin 2023
Leuchtturm
Neurologie

Effect of acute hypoxia exposure on the availability of A1 adenosine receptors in the human brain measured with [F-18]CPFPX PET

Authors

  • M. Michno

    1   Forschungszentrum Jülich, INM-2, Jülich

  • H. Weis

    2   Deutsches Zentrum für Luft- und Raumfahrt, kardiovaskuläre Luft- und Raumfahrtmedizin, Köln-Porz

  • J. Schmitz

    3   Deutsches Zentrum für Luft- und Raumfahrt, Schlaf und Humanfaktoren, Köln-Porz

  • A. Foerges

    1   Forschungszentrum Jülich, INM-2, Jülich

  • S. Beer

    1   Forschungszentrum Jülich, INM-2, Jülich

  • B. Neumaier

    4   Forschungszentrum Jülich, INM-5, Jülich

  • A. Drzezga

    5   Uniklinik Köln, Nuklearmedizin, Köln

  • D. Aeschbach

    3   Deutsches Zentrum für Luft- und Raumfahrt, Schlaf und Humanfaktoren, Köln-Porz

  • A. Bauer

    1   Forschungszentrum Jülich, INM-2, Jülich

  • J. Tank

    2   Deutsches Zentrum für Luft- und Raumfahrt, kardiovaskuläre Luft- und Raumfahrtmedizin, Köln-Porz

  • E. Elmenhorst

    3   Deutsches Zentrum für Luft- und Raumfahrt, Schlaf und Humanfaktoren, Köln-Porz

  • D. Elmenhorst

    1   Forschungszentrum Jülich, INM-2, Jülich
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Ziel/Aim Normobaric hypoxia induces numerous adaptive changes, e. g., in cerebral blood flow, metabolism and electrical activity. Adenosine, as an inhibitory neuromodulator, is produced in and/or released to the interstitial space during hypoxia and assumed to mediate several of these effects. A1 adenosine receptor (A1AR) antagonism or knock-out attenuates this neuronal inhibition in mice. Here we tested the hypothesis that exposure to an interval of hypoxia compared to an interval of normoxia (control) reduces the availability of A1AR in the human brain, due to hypoxia-triggered rise of endogenous adenosine. As exploratory objectives, we tested the hypotheses that psychomotor vigilance is affected during hypoxia and that cerebral blood flow is altered.

Methodik/Methods Ten healthy volunteers (32±13 years, 3f) completed an 110-min bolus plus constant infusion [F-18]CPFPX PET-MRI hybrid experiment: Subjects spent the first 60 minutes of the scan in normoxia followed by 30 minutes of individually adapted normobaric hypoxia to achieve a peripheral oxygen saturation of 70 - 75%, followed by 20 minutes of normoxia. Blood samples were used to calculate metabolite-corrected steady-state distribution volumes (VT) of A1AR (i. e., 40 – 100 min after start of [F-18]CPFPX administration). Brain perfusion was measured via arterial spin labelling. A 3-minute psychomotor vigilance test (PVT) was conducted every 10 minutes. Heart rate and peripheral blood oxygen saturation were measured continuously.

Ergebnisse/Results Hypoxia reduced A1AR availability in the cerebral cortex by 11% (p=0.033). Compared to normoxia, brain perfusion increased during hypoxia by 25% in cortical gray matter (p<0.001). Heart rate increased by 22% (p<0.001). PVT mean reaction time was longer by 7 ms (p=0.027).

Schlussfolgerungen/Conclusions Short term reduction of the oxygen saturation to 70% (corresponding to an oxygen saturation at an altitude of approximately 6000 m) increases cerebral blood flow and impairs cognitive performance while A1AR availability is reduced. This indicates that acute hypoxia exposure increases cerebral adenosine concentration and receptor occupancy.


Publication History

Article published online:
30 March 2023

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