New PET diagnosis of adenosine receptors in the brain, heart and skeletal muscle

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The purpose of the present study is to propose new PET diagnosis using [^<11>C]MPDX and [^<11>C]TMSX for imaging adenosine A_1 and A_<2A> receptors, respectively, in the brain, heart and muscle1. By applying [^<11>C]MPDX-PET and [^<11>C]TMSX-PET to normal subjects, A_1 and A_<2A> receptors, respectively, was quantitatively measured by compartment and graphical analyses using dynamic PET scan and serial arterial blood data.2. To avoiding invasive arterial blood sampling, a non-invasive quantitative method EPICA was successfully applied to both[^<11>C]MPDX-and [^<11>C]TMSX-PET.3. In the patients with Alzheimer's disease, a significantly decreased binding of [^<11>C]MPDX was observed in the bilateral medial temporal cortex and left temporo-parietal cortex. The decreased binding pattern of [^<11>C]MPDX was different from hypometabolism. In the patients with temporal lobe epilepsy, binding of [^<11>C]MPDX was significantly decreased in the mesial temporal lobe of focus side outside the hippocampus, but increased in the frontal cortex of focus side.4. In the patients with Parkinson's disease whose the left-side dopamine transporter was more decreased than the right side one, the dopamine D_2 receptors bindings was increased bilaterally, while the adenosine A_<2A> receptor was decreased on the left side.5. Following animal experiments, adenosine A_<2A> receptors in the heart and muscle were quantitatively evaluated in normal subjects. Adenosine A_<2A> receptor binding in the cardiac and skeletal muscles was greater in the endurance-trained men than in the untrained men.We concluded that [^<11>C]MPDX-PET and [^<11>C]TMSX-PET provides diagnostic tools of the physiological and pathological states of various diseases in term of adenosine receptors.