We accordingly sought to investigate the intrinsic arrhythmogenic effects of hypokalaemia in isolated, Langendorff-perfused wild-type (WT) mouse hearts for the first time by recording MAPs from endocardial and epicardial left ventricular sites.
Figure 4 shows sister sections through the mouse heart immunolabeled for Cx43 caveolin3 (myocyte marker) and HCN4, the ion channel responsible for the funny current (nodal marker).
Surprisingly, this regulatory region also interacts with the promoter of the next neighbouring gene, Enpep, which we show to be expressed in regions of the developing mouse heart essential for cardiac electrical activity.
The average percentage of uniquely mapped reads in the valid reads was 86.1% for the mouse cerebral cortex, 85.4% for the mouse cerebellum, 72.6% for the mouse heart, 78.1% for the chimpanzee cerebral cortex and 82.0% for the chimpanzee cerebellum (Additional file 1: Table S1, S2).
After we removed duplicate sequences, the average number of uniquely mapped reads in two replicates of each tissue sample was 19.2 million reads for the mouse cerebral cortex, 30.3 million reads for the mouse cerebellum, 18.1 million reads for the mouse heart, 19.0 million reads for the chimpanzee cerebral cortex and 22.5 million reads for the chimpanzee cerebellum.
Approximately 450 700 mg of grinded whole mouse heart was used for extraction of total RNA with 1 ml Trizol Reagent® (Invitrogen, Carlsbad, CA) following the manufacturer's instructions.
By screening and verifying their tissue expression patterns with microarray and real-time PCR analysis, six of 261 E3 ligases, including cardiac-specific Rnf207 and cardiac- and muscle-enriched Fbxo32/atrogin-1, Trim63/MuRF1, Trim63/MuRF1, Kbtbd10/KLHL41, Asb11 and Asb2 in mouse heart, were selected for the present study.
The RCR for mouse heart mitochondria using succinate as substrate was 4.087 for young mice heart and 3.76 for old mice heart using our isolation procedure which is similar to Rogers et al. (2011) with some modifications.
Therefore, mouse heart mitochondria were used for this purpose as a model suitable for toxicological testing.
Indeed, considering values from [8] as reference for mouse heart energetics, the measurement of the changes induced by any external effectors (e.g. hormone, pathology, etc) offers the possibility to access to internal regulations induced by this external effector on heart energetics (i.e. effects of decrease in oxygen availability in this study).
