Perinatal and Postnatal Expression of Cav1.3 α1D Ca2+ Channel in the Rat Heart

The novel Cav1.3 (alpha(1D)) L-type Ca2+ channel plays a significant role in sinoatrial (SA) and atrioventricular (AV) nodes function and in atrial fibrillation. However, the characterization of alpha(1D) Ca2+ channel during heart development is very limited. We used real-time RT-PCR, Western blotting, and indirect immunostaining to characterize the developmental expression and localization of alpha(1D) Ca2+ channel in rat hearts. Both protein and mRNA levels of am Ca2+ channel decreased postnatally. Two forms of alpha(1D) Ca2+ channel protein (250 and 190 kD) were observed, with the full-length (250 kD) channel protein being predominant in the prenatal stages. Both Western blots and confocal imaging demonstrated that alpha(1D) Ca2+ channel protein was expressed in both atria and ventricles at fetal and neonatal stages but was absent in the adult ventricles. Interestingly, alpha(1D) Ca2+ channel was also found at the nucleus/perinucleus of immature but not adult atrial cells. Furthermore, the nuclear staining was reproduced in adult atrial cell line, HL-1 cells, which possess immature properties. The data are first to show that alpha(1D) Ca2+ channel has unique age-dependent expression profile and subcellular localization in the heart, suggesting a developmental stage-dependent specific function. (Pediatr Res 69: 479-484,2011)