Cold acclimation alters [3h]norepinephrine uptake in brown adipose tissue

V. King, U. Samant, M. Fettinger, L. Cassis

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Previous studies demonstrated a decrease in [3H]norepinephrine (NE) uptake in interscapular brown adipose tissue (ISBAT) after 7 days of cold acclimation (CA). The purpose of this study was to determine the kinetics of the NE transporter in rat ISBAT after 7 days of cold acclimation at 4°C. [3H]NE uptake was determined by incubating oxygenated 500 jim ISBAT slices with [JH]NE (4 nM) for 10 min at 37°C. Unlabelled NE was added to acheive 8 different NE substrate concentrations. Nonspecific uptake was determined in the presence of nomifensine (10 /iM). The Km for [3H]NE uptake was not different between control and CA rats (control: 3.6 jtM; CA: 2.5 μM). The Vmax for fH]NE uptake in slices from control rats was 22 ± 2 pmoles/mg wt. In CA rats, two populations of NE transporters existed, one with an increased Vmax (52.4 ± 7 pmoles/mg) and one with a decreased Vmax (16.2 ± 2 pmoles/mg). In a separate group of rats plasma and ISBAT catecholamine [NE, dopamine (DA), epinephrine (EPI)] levels were determined. Plasma NE and DA were not significantly elevated in CA rats; however, plasma EPI was increased in CA rats (control: 2.6 ng/ml; CA: 6.5 ng/ml). ISBAT ME levels were increased in CA rats (control: 37 pg/ml; CA: 84 pg/ml). These results suggest differential regulation of the ISBAT NE transporter after 7 days of cold acclimation, potentially dependent on alterations in transporter substrate concentrations.

Original languageEnglish
Pages (from-to)A220
JournalFASEB Journal
Issue number3
StatePublished - 1996

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics


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