Molecular and Electrophysiological Differences in the L-Type Ca^<2+> Channel of the Atrium and Ventricle of Rat Hearts(EXPERIMENTAL INVESTIGATION)

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Background Many pathological conditions induce electrical remodeling, possibly through intracellular Ca^<2+> overload, but the currently available L-type Ca^<2+> channel blockers may be detrimental because of their global negative inotropic effects. Methods and Results To determine whether the L-type Ca^<2+> channel is identical throughout the heart, the distribution of the mRNAs and proteins comprising the L-type Ca^<2+> channel and its electrophysiological properties were analyzed in rat atria and ventricles. The mRNA of α2δ-2 (Cacna2d2) was more abundantly expressed in the atrium (〜5-fold) than in the ventricle. In contrast, α1C (Cacna1c) (Cav1.2) mRNA was significantly less abundant in the atrium. The level of the α1C (Cacna1c) (Cav1.2) protein was decreased (〜0.5-fold) and that of α2δ-1 (Cacna2d1) was increased (〜2-fold) in the atrium compared with the ventricle. Although the peak ICa, L density showed no significant differences, voltage dependence of inactivation and activation of the current showed a more depolarized shift in the atrium than in the ventricle. Conclusion These results indicate that in the rat heart the L-type Ca^<2+> channel differs between the atrium and ventricle with regard to gene expression and electrophysiological properties.
社団法人日本循環器学会の論文
2006-04-20