Heart norepinephrine content in iron deficiency anemia
1992
Smith, S.M. | Smith, S.H. | Beard, J.L.
Rat heart norepinephrine (NE) content is significantly diminished and Ne fractional turnover is decreased by dietary iron deficiency anemia at the same time that left ventricle size nearly doubles (Proc. Soc. Exp. Biol. Med. 193: 306-312, 1990). To determine if this low NE content is due to a) impaired synthesis per se, or b) mismatching of synthesis relative to adrenergic impulse traffic; we performed several experiments in which nerve traffic was altered through the use of a ganglionic blocking drug. in addition, we examined tyrosine hydroxylase activity both in vivo and in vitro. Heart NE concentration was 50% less than normal in the hypertrophied iron-deficient hearts (146 +/- 59 versus 481 +/- 72 ng NE/g). Ganglionic blockade for three hours resulted in similar elevations in NE contents in both dietary treatments. Pharmacologic inhibition of aromatic amino acid decarboxylase resulted in similar rates of dihydroxy phenyl alanine (DOPA) accumulation in hearts of anemic and control rats demonstrating equivalent in vivo tyrosine hydroxylase activities. In addition, in vitro tyrosine hydroxylase activity was similar. These findings demonstrate that norepinephrine synthesis per se is not defective in the iron-deficient heart but may still be limited in its capacity to match the demands of higher sympathetic activity.
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