title: Partition of thallium-201 in isolated myocardial tissue of rats previously injected at rest or after exercise.
abstract: The kinetics and distribution of TI-201 in isolated myocardial tissue of rats injected i.v. with this radionuclide are compared at rest and after exercise (2 hr of forced swimming). At 1/2 and 3 hr after injection, a myocardial segment was obtained and subjected to continuous washout with the radioactivity remaining in the tissue recorded each 10 sec for 1 hr. Altogether there were four groups of ten animals each. A three-compartment model (extracellular, main intracellular, and subcellular) was found to describe adequately the kinetics of TI-201. In the groups studied 1/2 hr after TI-201 injection the most dramatic effect of exercise was a translocation of TI-201 into the subcellular compartment. The change was also present but less marked in samples from exercised rats obtained 3 hr after TI-201 injection, which suggests a transition to the resting stage. The findings suggest the possibility of structural subcellular differences in myocardial uptake for TI-201 in clinical images visualized after exercise and at rest.
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D005110:Extracellular Space; D006321:Heart / Q000000981:diagnostic imaging; D007275:Injections, Intravenous; D007700:Kinetics; D008928:Mitochondria / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism* / Q000648:ultrastructure; D005082:Physical Exertion; D011868:Radioisotopes; D011877:Radionuclide Imaging; D051381:Rats; D012146:Rest; D013793:Thallium / Q000008:administration & dosage / Q000378:metabolism*
chemical_list: D011868:Radioisotopes; D013793:Thallium