Abstract
Objective–Chronic thiamine deficiency is believed to cause changes in the myocardium that could provoke arrhythmias. This study was undertaken to explore whether thiamine deprivation has a role in cardiac arrhythmogenesis. Methods–Isolated Langendorff-perfused rat heart preparations were used to determine whether or not thiamine-deprivation is associated with changes in cardiac function. We examined hearts isolated from thiamine-deprived, rescued and control rats. We measured heart rate, diastolic and systolic tension, contraction and relaxation rates, and coronary flow. Whole-cell voltage clamp was performed in isolated cells to measure L-type Ca2+ current. Results–The hearts from thiamine deficient rats did not degenerate into ventricular fibrillation during 30 minutes of reperfusion. The anti-arrhythmogenic effects were characterized by the arrhythmia severity index. The values for control, thiamine-deficient and rescued were 11 ± 1.0, 2 ± 0, and 10 ± 1.6 respectively. Ca2+ current density was smaller in thiamine-deprived cardiac myocytes. Our results suggest that hearts from thiamine-deprived rats did not experience irreversible arrhythmias. Conclusion–Thiamine deficiency seems to exert opposing effects on myocardial viability during ischemia-reperfusion insults with cardioprotection predominant over myocardial damaging. [Jpn J Physiol 55 Suppl:S105 (2005)]
