Nuclear Medicine Program progress report for quarter ending September 30, 1991

Rat tissue distribution properties of IQNP,'' a new radioiodinated cholinergic-muscarinic receptor antagonist, are described. IQNP is the acronym for 1-azabicyclo(2.2.2)oct-3-yl {alpha}-hydroxy-{alpha}-phenyl-{alpha}(1-iodo-1-propen-3-yl) acetate, which is an analogue of the QNB muscarinic antagonist in which the p-iodophenyl moiety has been replaced with the 1-iodo-1-propen-3-yl moiety. The radioiodinated IQNP analogue is easier to prepare in much higher yields than QNB and is thus a candidate for the evaluation of muscarinic receptors by external imaging techniques. Studies in rats demonstrated that IQNP shows high uptake in those cerebral regions rich in muscarinic receptors QNB-treatment of rats either 1 h before (pre) or 2 h after (post) administration of radioiodinated IQNP resulted in significant displacement or blocking of cerebral specific IQNP uptake (% dose/gm) in the cortex and striatum. These studies demonstrate that IQNP has specificity for the cholinergic-muscarinic receptor and is a good candidate for further studies. Also during this period, several agents developed in the ORNL Nuclear Medicine Program were supplied to Medical Cooperative Programs for collaborative studies including the iodine-125-labeled BMIPP and DMIPP fatty acid analogues and the IPM antibody labeling agent. Tin-117m and gold-199 were produced in the ORNL High Flux Isotope Reactor (HFIR) and supplied to the OHER-supported program inmore » the Medical Department at Brookhaven National Laboratory to aid in their research until the re-start of the High Flux Brookhaven Reactor.« less