Preliminary evaluation of 2-[4-[3-(tert-butylamino)-2-hydroxypropoxy]phenyl]-3-methyl-6-methoxy-4(3H)-quinazolinone ([+/-]HX-CH 44) as a selective beta 1-adrenoceptor ligand for PET

(+/-)-3-[C-11]Methyl-2-[4-[3-(tert-butylamino)-2 hydroxypropoxy]phenyl]-6-m ethoxy-4(3H)-quinazolinone ([+/-]-[C-11]HX-CH 44) was labeled with carbon-1 1 using [C-11]iodomethane with the corresponding N-demethylated precursor. Then, 30-90 mCi (1.10-3.33 GBq) of pure [C-11]HX-CH 44 were obtained 30 min after end of bombardment with Specific radioactivities of 500-1,400 mCi/mu mol (18.5-51.8 GBq/mu mol). Myocardial uptake in dogs was 0.340 +/- 0.043 pmol/mL tissue per nanomole injected, 10-15 min postinjection. Heart-to-lun g ratio was 3 from the 5th to the 30th minute. Only 35% of the myocardial r adioactivity could be displaced. Tissue uptake could not be blocked with ap propriate compounds. Therefore, (+/-)-[C-11]HX-CH 44 does not appear to be a suitable ligand for the study of myocardial beta 1-adrenoceptors in posit ron emission tomography. NUCL MED BIOL 26;1:105-109, 1999. (C) 1998 Elsevie r Science Inc.