Quantitative ARG microimaging studies of two muscarinic antagonist isomers: Blocking and the effects of cocaine
- Oak Ridge National Lab., TN (United States); and others
The distribution of the racemic mixture of IQNP(1-Azabicyclo [2-2-2] oct-3-yl alpha-hydroxy-alpha-(1-iodo-propen-3-yl)-alpha-phenylacetate), a muscarinic antagonist was described earlier. Recently, the radioiodinated Z and E-(R,R) IQNP isomers have been prepared. Quantitative ARG studies using the Z and E isomers were performed in control rats and after pretreatment with ({plus_minus}) QNB or cocaine. High uptake of (Z)-IQNP was seen in the heart and brain with GI and urinary excretion. Lung uptake was lower than with the racemic IQNP. (Z)-IQNP uptake was maximal at 15 min p.i. with homogeneous distribution in the heart. In the brain, highest uptake was in the caudate, cortex, hippocampus, pons and thalamus. (Z)-IQNP showed higher cerebellar uptake and lower cortical uptake compared to (E)-IQNP. Clearance from brain was slower than bean. Heart and brain uptake of (E)-IQNP were markedly lower than the Z isomer. After QNB pretreatment, almost complete blocking of (Z)-IQNP uptake in heart and brain occurred. Cocaine did not significantly affect the distribution of IQNP. These data indicate that (Z)-IQNP has high affinity for the M2 muscarinic receptor with potential for brain and heart imaging. Cocaine appears to have little effect on the muscarinic-cholinergic receptors in the brain and heart.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States)
- DOE Contract Number:
- AC02-76CH00016; AC05-84OR21400
- OSTI ID:
- 198049
- Report Number(s):
- CONF-940605-; ISSN 0161-5505; TRN: 95:007029-0196
- Journal Information:
- Journal of Nuclear Medicine, Vol. 35, Issue Suppl.5; Conference: 41. annual meeting of the Society of Nuclear Medicine, Orlando, FL (United States), 5-8 Jun 1994; Other Information: PBD: May 1994
- Country of Publication:
- United States
- Language:
- English
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