Adrenal medulla imaging agents: a structure-distribution relationship study of radiolabeled aralkylguanidines
Fourteen /sup 125/I-labeled aralkylguanidines were synthesized and evaluated as potential imaging agents for the adrenal medullae and tumors of adrenomedullary origin. These guanidines are radiotracer analogues of guanethidine, an antihypertensive agent thought to mediate neuron blockade by uptake into adrenergic nerves. Dog adrenal medullae were used as a model to test radiotracer affinity for catecholamine storage tissue. Tissue distribution studies revealed that a number of radioiodinated guanidines showed pronounced localization in the adrenal medullae following intravenous injection, in certain cases exceeding that of either (-)-(/sup 3/H)norepinephrine or (/sup 14/C)guanethidine. (m-(/sup 125/I)Iodobenzyl)guanidine (m-IBG, 2b) gave the best combination of high concentration and selectivity. The low adrenomedullary affinity observed with (/sup 14/C)guanidine and m-(/sup 125/I)iodobenzylamine demonstrates the uniqueness of the aralkylguanidine structure. Preliminary evidence suggests that 2b is a storage analogue of norepinephrine. (/sup 125/I)2a is now being used clinically in imaging and radiotherapy of catecholamine tumors, such as pheochromocytoma.
- Research Organization:
- Univ. of Michigan Medical Center, Ann Arbor
- OSTI ID:
- 6746983
- Journal Information:
- J. Med. Chem.; (United States), Vol. 27:2
- Country of Publication:
- United States
- Language:
- English
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NEOPLASMS
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TRITIUM COMPOUNDS
ANIMALS
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550601* - Medicine- Unsealed Radionuclides in Diagnostics