Uptake of 1-deoxy-1-[125I]iodo-D-mannoheptulose by different cell types: in vitro and in vivo experiments.
D-mannoheptulose was recently proposed as a tool to label preferentially insulin-producing cells in the pancreatic gland in the perspective of the non-invasive imaging of the endocrine pancreas. In such a perspective, we have now synthesized 1-deoxy-1-[125I]iodo-D-mannoheptulose ([125I]MH) and examined its uptake by different rat cell types. No phosphorylation of [125I]MH by bovine heart hexokinase could be detected. The apparent distribution space of [125I]MH largely exceeded that of [U-14C]sucrose, considered as an extracellular marker, in erythrocytes, parotid cells, hepatocytes, pancreatic pieces and isolated pancreatic islets. Relative to the mean intracellular distribution space of 3HOH, that of [125I]MH was not significantly different in pancreatic pieces from either normal rats or streptozotocin-induced diabetic animals (STZ rats). In pancreatic islets, the uptake of [125I]MH was decreased at low temperature, but failed to be significantly affected by cytochalasin B. Sixty min after the intravenous injection of [125I]MH, the radioactive content of selected organs displayed the following hierarchy: muscle<pancreas<liver<parotid<kidney<plasma. In this respect, there was no obvious difference between control and STZ rats. Taken as a whole, these findings suggest that 1-deoxy-1-[125I]iodo-D-mannoheptulose does not display the same specificity towards GLUT2, as that previously documented in the case of D-[3H]- mannoheptulose.
Sener
A
A
Laboratory of Experimental Medicine, Brussels Free University, Brussels, Belgium.
Bessieres
B
B
Courtois
P
P
Ladriere
L
L
Louchami
K
K
Jijakli
H
H
Malaisse
W J
WJ
D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism; D004912:Erythrocytes / Q000166:cytology / Q000378:metabolism; D022781:Hepatocytes / Q000166:cytology / Q000378:metabolism; D006593:Hexokinase / Q000378:metabolism; D007457:Iodine Radioisotopes; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism; D008356:Mannoheptulose / Q000737:chemistry / Q000378:metabolism / Q000493:pharmacokinetics*; D010179:Pancreas / Q000378:metabolism; D010306:Parotid Gland / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D013997:Time Factors; D014018:Tissue Distribution
D007457:Iodine Radioisotopes; D008356:Mannoheptulose; D006593:Hexokinase