OBJECTIVETo investigate the expression of divalent metal transporter 1 (DMT1) mRNA in male Sprague-Dawley rat heart of different ages and the expression of DMT1 regulated by dietary iron.

METHODSReverse transcriptase (RT)-PCR and Western blot were used in this study.

RESULTS(1)Two isoforms of DMT1 mRNA [with and without iron-responsive element (IRE)] were both detected in rat heart, which were correlated with heart iron content. During development, both of two isoforms of DMT1 mRNA expression were the lowest at the age of PND 7, and increased at PND 21, 63 to 196. (2) After fed with a high iron diet or low iron diet for 6 weeks, the rats developed iron overload or iron deficiency respectively. No significant differences in DMT1 mRNA expression were detected among iron overload, iron deficiency and control rats. By using Western blot analysis, a 21% and 40% reduction in DMT1 protein non IRE form and IRE form respectively were found in iron overload rat (P<0.01, compared with control). Increases (26% approximate, equals 28%) in the levels of two isoforms of DMT1 protein were also observed in iron deficient rat (P<0.01, compared with control).

CONCLUSIONThe level of DMT1 mRNA expression in heart is age dependent;the two isoforms of DMT1 protein may be both regulated by iron on the posttranscriptional mechanism.