Regional uptake of iodine-125-metaiodobenzylguanidine in the rat heart

Regional uptake of iodine-125-metaiodobenzylguanidine ([125I]MIBG) was evaluated in normal (n = 12) and reserpinized (n = 12) rat hearts. At 15 min and 1, 3 and 6 h after injection of [125I]MIBG, tissue activities were calculated for the right ventricular myocardium (RV), the whole left ventricular...

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Bibliographic Details
Published in:European Journal of Nuclear Medicine 1993-11, Vol.20 (11), p.1104-1107
Main Authors: MATSUNARI, I, BUNKO, H, TAKI, J, NAKAJIMA, K, MURAMORI, A, KUJI, I, MIYAUCHI, T, TONAMI, N, HISADA, K
Format: Article
Language:English
Subjects:
3-Iodobenzylguanidine
Animals
Biological and medical sciences
Cardiovascular system
Endocardium - innervation
Heart - drug effects
Investigative techniques, diagnostic techniques (general aspects)
Iodine Radioisotopes
Iodobenzenes - pharmacokinetics
Male
Medical sciences
Myocardium - metabolism
Radionuclide investigations
Rats
Rats, Sprague-Dawley
Reserpine - pharmacology
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Summary:Regional uptake of iodine-125-metaiodobenzylguanidine ([125I]MIBG) was evaluated in normal (n = 12) and reserpinized (n = 12) rat hearts. At 15 min and 1, 3 and 6 h after injection of [125I]MIBG, tissue activities were calculated for the right ventricular myocardium (RV), the whole left ventricular myocardium (whole LV), the epicardial layer of the left ventricular myocardium (Ep LV), the endocardial layer of the left ventricular myocardium (En LV), the basal segment of the left ventricular myocardium and the apical segment of the left ventricular myocardium. The uptake of [125I]MIBG at 6 h after injection in the normal rat heart was higher in RV than in whole LV (0.45 +/- 0.09% vs 0.30 +/- 0.06% kg dose/g), and in Ep LV than in En LV (0.32 +/- 0.07% vs 0.25 +/- 0.05%). In the reserpinized rat heart, the difference in the uptake between Ep LV and En LV was smaller. This suggests that the difference in the regional [125I]MIBG uptake might reflect different intravesicular uptake in the layers of the heart. To our knowledge, the low uptake in the endocardial layer was a new finding which seems to indicate a difference in innervation between the epicardial and endocardial layers of the left ventricle in the rat heart. Autoradiographic study also showed the low uptake of [125I]MIBG in the endocardial layer, while homogeneous perfusion was observed with thallium-201, supporting the tissue uptake study. Thus, the endocardial and epicardial layers of the left ventricle in the rat heart were considered to be differently innervated.
ISSN:0340-6997
1619-7089
DOI:10.1007/bf00173491