title: Metaiodobenzylguanidine as an index of the adrenergic nervous system integrity and function.
abstract: The radiopharmaceutical, metaiodobenzylguanidine (MIBG) acts as an analog of norepinephrine (NE). Experiments in rats were carried out to determine how closely the movements of [125I]MIBG in the heart mimicked those of [3H]NE, and if the changes [125I] MIBG concentrations would reflect injury to, and function of, adrenergic neurons in the heart. Injury to adrenergic neurons by 6-hydroxydopamine substantially reduced the uptake of [125I] MIBG into the left ventricle, but the effect was less than that on uptake of [3H]NE uptake and concentration of endogenous NE. Similarly, when desmethylimipramine was given to inhibit the uptake-1 pathway of neurons, the reduction in uptake of [125I]MIBG was statistically significant but less than that of [3H]NE; part of this difference may be attributable to partial uptake of [125I]MIBG into neurons by a diffusion pathway. Substantial fractions of [125I]MIBG and [3H]NE were displaced from the heart by the sympathomimetic drug, phenylpropanolamine. When adrenergic neurons of the heart were stimulated by feeding of rats, the disappearance rates of [3H]NE and [125I]MIBG from the heart were significantly increased. Although not a perfect analog of [3H]NE, [125I]MIBG appears to enter and leave the heart in patterns similar to those of [3H]NE. Thus, movements of [125I]MIBG give indices of adrenergic neuron injury and function in the heart.
authors: Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0028.
authors: J C
authors: JC
authors: Sisson
authors: D M
authors: DM
authors: Wieland
authors: P
authors: P
authors: Sherman
authors: T J
authors: TJ
authors: Mangner
authors: M C
authors: MC
authors: Tobes
authors: S
authors: S
authors: Jacques
mesh_terms: D019797:3-Iodobenzylguanidine; D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D003891:Desipramine / Q000494:pharmacology; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D006892:Hydroxydopamines / Q000494:pharmacology; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D010665:Phenylpropanolamine / Q000494:pharmacology; D011877:Radionuclide Imaging; D051381:Rats
chemical_list: D006892:Hydroxydopamines; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D010665:Phenylpropanolamine; D019797:3-Iodobenzylguanidine; D003891:Desipramine