Norepinephrine turnover in iron deficiency at three environmental temperatures.
Iron-deficient anemic rats had a significant elevation in urinary norepinephrine (NE) after 7 days at 30 and 24 degrees C, but not at 10 degrees C, compared with control animals. NE turnover studies were performed to examine sympathetic nervous system activity in a tissue-specific fashion. NE content in myocardium decreased by nearly 50% in hypertrophied iron-deficient hearts at all three temperatures, whereas fractional turnover rates were compensatorily increased. In contrast, interscapular brown adipose tissue NE turnover was significantly reduced to 30% of normal in iron-deficient animals at both 30 and 10 degrees C. Serum triiodothyronine concentrations were similar to controls at 30 degrees C but were decreased at lower temperatures. Serum tetraiodothyronine concentrations were lower in iron-deficient animals at all three environmental temperatures. We conclude that increased sympathetic nervous system activity compensatory to temperatures below thermoneutrality is less well controlled in iron-deficient animals than in controls, and at a low environmental temperature this may possibly explain the poor thermoregulatory capacity of iron-deficient animals. A generalized hypernoradrenergic state is not supported by our NE turnover study and does not explain the elevated urine NE concentrations.
Beard
J
J
Nutrition Program, The Pennsylvania State University, University Park 16802.
Tobin
B
B
Smith
S M
SM
D000273:Adipose Tissue / Q000378:metabolism; D002001:Adipose Tissue, Brown / Q000378:metabolism; D000747:Anemia, Hypochromic / Q000652:urine*; D000818:Animals; D004032:Diet; D008297:Male; D009206:Myocardium / Q000378:metabolism; D009638:Norepinephrine / Q000652:urine*; D051381:Rats; D011919:Rats, Inbred Strains; D013696:Temperature
D009638:Norepinephrine