Myocardial adenosine A2a receptor imaging of rabbit by PET with [11C]KF17837.
Adenosine A2a receptors are found in the endothelia, vascular smooth muscle cells and cardiac myocytes. The properties of a carbon-11 labeled A2a antagonist [11C]KF17837 ([7-methyl-11C](E)-8-(3,4-dimethoxystyryl)-1,3-dipropyl-7-methy lxa nthine) for myocardial imaging were evaluated by dynamic PET scanning of the myocardium in rabbits. Myocardial uptake of [11C]KF17837 was clearly visualized by PET. The tracer was taken up at a high level by the myocardium immediately after the injection, and the myocardial level of radioactivity gradually decreased. On the other hand, an inactive [11C]Z-isomer of [11C]KF17837 showed a very low myocardial uptake and the myocardium was not visualized with a selective A1 antagonist [11C]KF15372. By co-injection with carrier KF17837 or a xanthine type A2a antagonist 7-chlorostyrylcaffeine (CSC), the myocardial uptake of [11C]KF17837 was completely blocked. The effect of non-xanthine A2a antagonists ZM 241,385 and SCH 58,261, which have a higher affinity than CSC, was smaller than that of the CSC. The effect of weak antagonists caffeine and alloxazine or a xanthine type A1 antagonist KF15372 on the radioactivity level was small. It is concluded that PET with [11C]KF17837 can image myocardial adenosine A2a receptors.
Ishiwata
K
K
Positron Medical Center, Tokyo Metropolitan Institute of Gerontology, Japan. ishiwata@pet.tmig.or.jp
Sakiyama
Y
Y
Sakiyama
T
T
Shimada
J
J
Toyama
H
H
Oda
K
K
Suzuki
F
F
Senda
M
M
D000818:Animals; D002250:Carbon Radioisotopes; D006321:Heart / Q000000981:diagnostic imaging*; D009206:Myocardium / Q000737:chemistry; D058915:Purinergic P1 Receptor Antagonists; D011817:Rabbits; D018047:Receptors, Purinergic P1 / Q000378:metabolism; D014055:Tomography, Emission-Computed / Q000379:methods*; D014970:Xanthines / Q000737:chemistry
D002250:Carbon Radioisotopes; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D014970:Xanthines; C081198:KF 17837