title: Studies of origins of abnormal sympathetic function in obese Zucker rats.
abstract: To explain previously described abnormalities of sympathetic function in the genetically obese Zucker rat, the kinetics of norepinephrine (NE) metabolism were examined. Lower stress-induced levels of plasma NE in the obese rat were shown to be due to decreased release of NE because uptake of [3H]NE tracer from plasma was 45% slower in the obese compared with the lean rat. NE levels were 15, 20, and 34% lower in heart, pancreas, and interscapular brown adipose tissue (IBAT), and NE turnover rates (determined by two independent methods) were 39-48 and 43-69% lower in the pancreas and IBAT of obese compared with lean rats. In vivo synthesis of [3H]NE from [3H]dopamine by the enzyme dopamine beta-hydroxylase was 60% lower in IBAT but was equal in hearts of obese compared with lean rats. These results suggest an organ-specific decrease of NE synthesis in the obese Zucker rat, possibly due to decreased dopamine beta-hydroxylase activity in IBAT.
mesh_terms: D000273:Adipose Tissue / Q000378:metabolism; D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D004298:Dopamine / Q000378:metabolism*; D006579:Heterozygote; D006720:Homozygote; D007700:Kinetics; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000378:metabolism*; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D010179:Pancreas / Q000378:metabolism; D051381:Rats; D011924:Rats, Zucker; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D014316:Tritium
chemical_list: D014316:Tritium; D004298:Dopamine; D009638:Norepinephrine