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Psychopharmacology (Berl). 2001 Aug;157(1):111-4.

The in vitro pharmacology of the beta-adrenergic receptor pet ligand (s)-fluorocarazolol reveals high affinity for cloned beta-adrenergic receptors and moderate affinity for the human 5-HT1A receptor.

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Department of Biochemistry, Rm W438, Case Western Reserve University Medical School, 10900 Euclid Avenue, Cleveland, OH 44106-4935, USA.



s-Fluorocarazolol [(S)-FCZ] is the major positron emission tomography (PET) ligand currently used to visualize central beta-adrenergic receptors in vivo, although its pharmacology is incompletely known.


Our objective was to comprehensively characterize the in vitro pharmacology of (S)- and (R)-FCZ to determine its suitability for study of central and peripheral beta-adrenergic receptors.


We characterized the in vitro pharmacology of (S)-FCZ at 42 biogenic amine receptors and transporters in vitro using the resources of the National Institute of Mental Health Psychoactive Drug Screening Program.


As expected (R)- and (S)-FCZ had high affinities for beta-adrenergic receptors (Ki values=0.08-0.45 nM) and negligible affinities (Ki values>100 nM) for nearly all other tested receptors and transporters with the exception of the h5-HT1A receptor for which (S)-FCZ had high affinity (Ki=34 nM). Interestingly, (R)-FCZ had low affinity for the h5-HT1A receptor (Ki=342 nM).


The high affinity of (S)-FCZ for the h5-HT1A receptor is not likely to interfere with studies of peripheral beta-adrenergic receptors, since 5-HT1A receptors are expressed at very low levels outside the central nervous system. Indeed, computer simulations predict that even at low ligand concentrations, 5-HT1A binding in brain regions like hippocampus are likely to be substantial. Thus, (S)-FCZ may not be a suitable PET ligand for studies of central nervous system beta-adrenergic receptors unless the contribution by 5-HT1A sites can be shown to be negligible.

[Indexed for MEDLINE]

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