Demonstration of pulmonary beta2-adrenergic receptor binding in vivo with [18F]fluoroethyl-fenoterol in a guinea pig model.
OBJECTIVE
The new beta2 radioligand (R,R)(S,S) 5-(2-(2-[4-(2-[18F]fluoroethoxy)phenyl]-1-methylethylamino)-1-hydroxyethyl)-benzene-1,3-diol ([18F]FE-fenoterol; [18F]FEFE), a fluoroethylated derivative of racemic fenoterol, was evaluated in vivo and ex vivo using a guinea pig model.


METHODS
Dynamic PET studies over 60 min with [(18)F]FEFE were performed in nine Hartley guinea pigs in which a baseline (group 1, n=3), a predose (group 2, n=3; 2 mg/kg fenoterol 5 min prior to injection of [18F]FEFE) or a displacement study (group 3, n=3; 2 mg/kg fenoterol 5 min post injection of [18F]FEFE) was conducted.


RESULTS
In all animal groups, the lungs could be visualised and semi-quantified separately by calculating uptake ratios to non-specific binding in the neck area. Premedication with non-radioactive fenoterol and displacement tests showed significant reduction of lung uptake, by 94% and 76%, respectively.


CONCLUSIONS
These data demonstrate specific binding of the new radioligand to the pulmonary beta2-receptors in accordance with ex vivo measurements. Therefore, [18F]FEFE seems to be suitable for the in vivo visualisation and quantification of the pulmonary beta2-receptor binding in this animal model.
Helisch
A
A
Department of Nuclear Medicine, University Hospital, Langenbeckstrasse 1, 55101 Mainz, Germany. helisch@nuklear.klinik.uni-mainz.de
Schirrmacher
E
E
Thews
O
O
Schirrmacher
R
R
Buchholz
H G
HG
Dillenburg
W
W
Höhnemann
S
S
Tillmanns
J
J
Wessler
I
I
Buhl
R
R
Rösch
F
F
Bartenstein
P
P
D000818:Animals; D005240:Feasibility Studies; D005280:Fenoterol / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D006168:Guinea Pigs; D008168:Lung / Q000000981:diagnostic imaging* / Q000378:metabolism*; D008657:Metabolic Clearance Rate; D023421:Models, Animal; D009928:Organ Specificity; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D014018:Tissue Distribution
C509462:(R,R)(S,S)-5-(2-(2-(4-(2-(18F)fluoroethoxy)phenyl)-1-methylethylamino)-1-hydroxyethyl)-benzene-1,3-diol; D019275:Radiopharmaceuticals; D018343:Receptors, Adrenergic, beta-2; D005280:Fenoterol