title: Discrepancies in the extracellular space of sympathetic ganglia measured using different isotopes of mannitol and sucrose.
abstract: The extracellular space of rat superior cervical ganglia in vitro was measured using mannitol and sucrose labelled with tritium and carbon-14. The volumes of distribution of the 3H-labelled derivatives, especially [3H]mannitol, exceeded those of the 14C-derivatives. The divergence increased with increasing lengths of incubation. Thus, after 30 min incubation, 'spaces' (ml . g-1) were: [14Cu]mannitol, 0.407; [3H]mannitol 0.447; [14C]mannitol, 0.458; [3H]mannitol, 0.645; [14C]sucrose, 0.430; [3H]sucrose, 0.497. Using thin layer chromatography, it was shown that an average of 22% of the label in ganglia incubated for 120 min with [3H]mannitol, but only 4% with [14C]mannitol, was not associated with the parent compound. Both [3H]- and [14C]sucrose appeared to be metabolized by 11%. It is concluded that mannitol and sucrose can be metabolized in isolated ganglia and that this may lead to substantial errors in estimating the extracellular space, particularly when [3H]markers are used.
mesh_terms: D000818:Animals; D002250:Carbon Radioisotopes; D005110:Extracellular Space / Q000378:metabolism*; D005728:Ganglia, Sympathetic / Q000378:metabolism*; D008297:Male; D008353:Mannitol / Q000378:metabolism*; D051381:Rats; D013395:Sucrose / Q000378:metabolism*; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D014316:Tritium; D008353:Mannitol; D013395:Sucrose