AJP - Regulatory, Integrative and Comparative Physiology, Vol 255, Issue 1 90-R96, Copyright © 1988 by American Physiological Society

ARTICLES

Norepinephrine turnover in iron deficiency at three environmental temperatures

J. Beard, B. Tobin and S. M. Smith
Nutrition Program, The Pennsylvania State University, University Park 16802.

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.

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