Regional Differences in Expression of L-type Ca^ Channel α_1 Subunits in Mouse Heart

L-type Ca 2 + channels (LTCCs) play essential roles in excitation and contraction. Four different α 1 subunits (α 1 S , α 1 C , α 1 D and α 1 F ) have been recoginized for the pore forming subunit of LTCC. We investigated mRNA expression of the four subunits in adult mouse heart (the left ventricle, the right appendage and the SA node region) using RT-PCR. α 1 C mRNA was expressed in all examined regions. α 1 D mRNA was detected in sinoatrial (SA) node as well as in right atrium, but not in the ventricle. Expressions of α 1 S and α 1 F mRNAs were below the level of detection at any sites. This observation suggests differential expression and different roles of LTCCs composed of α 1 C and α 1 D subunits in the mammalian hearts.