Document Detail


Kinetics of radioiodinated species in subcellular fractions from rat hearts following administration of iodine-123-labelled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (123I-BMIPP).
MedLine Citation:
PMID:  8612657     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
It is recognized that iodine-123-labelled 15-(p-iodophenyl)-3-(R,S)-methylpentadecanoic acid (123I-BMIPP) slowly washes out of the myocardium. The mechanism for the washout was investigated in normal rat hearts by analyses of the subcellular distribution and lipid classes based on the BMIPP metabolism. Rat hearts were excised at 1-120 min after intravenous injection of 123I-BMIPP. After counting the radioactivity, the hearts were digested with Nagarse and homogenized, and then fractionated into the cytosolic, mitochondrial, microsomal and crude nuclear fractions by centrifugations. The radioactivity of each fraction was counted, and the lipid classes were analysed by radio-thin-layer chromatographic and high-performance liquid chromatographic methods. The heart uptake of 123I-BMIPP was maximal at 5 min (6.81%+/-0.36% ID/g), and 41% of the radioactivity disappeared within 120 min. The myocardial radioactivity was immediately distributed into the cytosolic, mitochondrial, microsomal and crude nuclear fractions. The distribution (%) of each fraction was almost identical from 5 min through 120 min. The cytosolic fraction was always the major site of radioactivity deposition (60%), and the time-activity curve of the cytosolic fraction paralleled that of the whole heart throughout the 120-min study period. In the cytosolic fraction, most of the radioactivity was incorporated into the triglyceride class, and the rest was present in the free fatty acid, phospholipid (phosphatidylcholine) and diglyceride classes. In the mitochondrial fraction, the radioactivity was mostly incorporated into the phospholipid class (phosphatidylethanolamine), followed by free fatty acids. The final metabolite of 123I-BMIPP, 123I-p-iodophenylacetic acid (123I-PIPA), initially appeared in the mitochondrial fraction as early as 1 min, and subsequently in the cytosolic fraction at 5 min. Another intermediary metabolite, 123I-p-iodophenyldodecanoic acid (123I-PIPC12), was found only in the mitochondrial fraction after 5 min. In conclusion, the slow washout kinetics of 123I-BMIPP from the myocardium mainly reflects the turnover rate of the triglyceride pool in the cytosol. The BMIPP metabolism, i.e. initial alpha-oxidation followed by subsequent cycles of beta-oxidation, was confirmed in vivo. The participation of the mitochondria in the metabolism was also proven.
Authors:
S Morishita; H Kusuoka; Y Yamamichi; N Suzuki; M Kurami; T Nishimura
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  European journal of nuclear medicine     Volume:  23     ISSN:  0340-6997     ISO Abbreviation:  Eur J Nucl Med     Publication Date:  1996 Apr 
Date Detail:
Created Date:  1996-06-06     Completed Date:  1996-06-06     Revised Date:  2006-05-06    
Medline Journal Info:
Nlm Unique ID:  7606882     Medline TA:  Eur J Nucl Med     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  383-9     Citation Subset:  IM    
Affiliation:
Central Research Laboratory, Nihon Medi-Physics Co., Ltd., 3-1 Kitasode, Sodegaura, Chiba, 299-02, Japan.
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MeSH Terms
Descriptor/Qualifier:
Animals
Chromatography, Thin Layer
Cytosol / chemistry
Fatty Acids / diagnostic use,  pharmacokinetics,  pharmacology*
Female
Iodine Radioisotopes / diagnostic use*
Iodobenzenes / diagnostic use,  pharmacokinetics,  pharmacology*
Mitochondria, Heart / chemistry
Myocardium / ultrastructure*
Rats
Rats, Sprague-Dawley
Subcellular Fractions / metabolism*,  radiation effects*
Chemical
Reg. No./Substance:
0/Fatty Acids; 0/Iodine Radioisotopes; 0/Iodobenzenes; 116754-87-1/iodofiltic acid

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