Figure 3. Generation and evaluation of the β1D^−/− mouse model under basal conditions.

(A) Schematic of the targeting vector and generation of β1D^−/− mice. (B) RT-PCR analysis of integrin β1D mRNA in ventricle samples from WT (Cre⁻/Itgb1^f/f) and β1D^−/− (Cre⁺/Itgb1^f/f) mice. (C) Representative immunostaining for integrin β1D and nuclei in left ventricular tissue sections from β1D^−/− and WT mice (Blue, DAPI stained nuclei; Red, β1D). Heart tissues were collected from mice two weeks after the last dose of tamoxifen injection. (D) Representative immunoblots for integrin β1D, total RyR2, pRyR2 Ser-2030, pRyR2 Ser-2808, pRyR2 Ser-2814 and GAPDH protein levels in left ventricular tissue homogenates from WT and β1D^−/− mice. (E-H) Quantitative assessment of the protein levels represented in (D). n=4 hearts/genotype. (I) Representative DHPR and RyR2 immunostaining of WT and β1D^−/− isolated cardiomyocytes. (J) Representative Di-8-ANEPPS immunostaining of WT and β1D^−/− isolated cardiomyocytes. (K) Mean TT power values, where TT power indicates the strength of the regularity of the T-tubule network. n=25–30 cells from 3 hearts/genotype. The data represent the means ± SEM; **P<0.01; ***P<0.001; n. s., not significant; Student’s t test. Abbreviations: β1D, integrin β1D; β1D^−/−, integrin β1D knockout; GAPDH, glyceraldehyde 3-phosphate dehydrogenase; RT-PCR, reverse transcriptase coupled polymerase chain reaction; DHPR, Dihydropyridine (L-type Ca²⁺ channel); RyR2, Ryanodine Receptor 2.