Cardiac structural changes and electrical remodeling in a thiamine-deficiency model in rats

Aims: Thiamine is an important cofactor present in many biochemical reactions, and its deprivation can lead to heart dysfunction. Little is known about the influence of thiamine deprivation on the electrophysiological behavior of the isolated heart cells and information about thiamine deficiency in heart morphology is controversial. Thus, we decided to investigate the major repolarizing conductances and their influence in the action potential (AP) waveform as well as the changes in the heart structure in a set of thiamine deficiency in rats. Main methods: Using the patch-clamp technique, we investigated inward (I-K1) and outward K+ currents (I-to), T-type and L-type Ca2+ currents and APs. To evaluate heart morphology we used hematoxylin and eosin in transversal heart sections. Key findings: Thiamine deficiency caused a marked decrease in left ventricle thickness, cardiomyocyte number, cell length and width, and membrane capacitance. When evaluating Ito we did not find difference in current amplitude; however an acceleration of I-to inactivation was observed. I-K1 showed a reduction in the amplitude and slope conductance, which implicated a less negative resting membrane potential in cardiac myocytes isolated from thiamine-deficient rats. We did not find any difference in L-type Ca2+ current density. T-type Ca2+ current was not observed. In addition, we did not observe significant changes in AP repolarization. Significance: Based on our study we can conclude that thiamine deficiency causes heart hypotrophy and not heart hypertrophy. Moreover, we provided evidence that there is no major electrical remodeling during thiamine deficiency, a feature of heart failure models. (C) 2009 Elsevier Inc. All rights reserved.