PT  - JOURNAL ARTICLE
AU  - Sven Sihver
AU  - Wiebke Sihver
AU  - Mats Bergström
AU  - A. Urban Höglund
AU  - Pernilla Sjöberg
AU  - Bengt Långström
AU  - Yasuyoshi Watanabe
TI  - Quantitative Autoradiography with Short-Lived Positron Emission Tomography Tracers: A Study on Muscarinic Acetylcholine Receptors with<em>N</em>-[<sup>11</sup>C]methyl-4-piperidylbenzilate
DP  - 1999 Aug 01
TA  - Journal of Pharmacology and Experimental Therapeutics
PG  - 917--922
VI  - 290
IP  - 2
4099  - http://jpet.aspetjournals.org/content/290/2/917.short
4100  - http://jpet.aspetjournals.org/content/290/2/917.full
SO  - J Pharmacol Exp Ther1999 Aug 01; 290
AB  - The present work demonstrates quantitative autoradiography by using positron emission tomography tracers and storage phosphorimaging plates. The uptake and association of [11C]N-methyl-4-piperidylbenzilate was measured in rat brain tissue cryosections of various thicknesses. The signal increased with increasing section thickness, but only in 10-μm-thick sections did the binding reach the steady state during a 50-min observation time. This violation of the equilibrium condition, potentially combined with perfusion limitations, leads to erroneous increased binding-site density and decreased affinity in the 25- and 50-μm-thick sections. For better imaging of receptor distribution it is reasonable to use thicker sections. For quantitative analysis of receptor-binding parameters, the specific properties of ligands at different thicknesses of cryosections need to be considered. Evidence is provided that the nonselective muscarinic antagonistN-methyl-4-piperidylbenzilate binds preferentially to the M4 subtype of muscarinic acetylcholine receptors. The American Society for Pharmacology and Experimental Therapeutics