Figure 3: Characterization of the DN-MCU transgenic mouse.
From: The mitochondrial uniporter controls fight or flight heart rate increases
(a) Schematic of the α-myosin heavy chain promoter-driven transgenic DN-MCU construct. (b) Western blots for Myc-tagged DN-MCU protein from heart (H), liver (L) and skeletal muscle (S) lysates (WT, n=3; DN-MCU, n=3). (c) Summary echocardiographic data showing mean±standard deviation (WT, n=21; DN-MCU, n=20). NS was identified in any parameter: heart rate (HR), ejection fraction (EF), left ventricular mass (LV mass), end diastolic volume (EDV), end systolic volume (ESV), stroke volume (SV) and cardiac output (CO). (d) Images show 10 μm sections through the SAN area. Anti-Myc (green) antibody identified cells expressing DN-MCU and the SAN was identified by anti-HCN4 enhancement (red stain). Scale bar, 50 μm. (e) Data show ATP concentrations measured in freshly isolated atrial tissue from DN-MCU and littermate WT mice. ****P<0.0001, unpaired Student‘s t-test. (f,g) Representative Ca2+ uptake tracings of three similar experiments in permeabilized cardiac myocytes from DN-MCU and littermate WT mice (as in Supplementary Fig. 2). Arrows represent the addition of Ca2+ (100 μM). (h,i) Example in vivo ECG tracings recorded under basal (left) and ISO-stimulated (right) conditions from DN-MCU and littermate WT mice. Scale bar, 100 ms. (j) Summary data for in vivo heart rate response to ISO (10 μg kg−1). Solid bars represent baseline and hashed bars represent ISO response. *P<0.05, **P<0.01, ***P<0.001, paired Student‘s t-test, n=5–6 per group, error bars indicate s.e.m. (k) Percentage rate increases over baseline after ISO in in vivo ECG recordings (data calculated from j). (l) In vivo heart rate response to activity was reduced in DN-MCU mice, n=8–11 per group. *P<0.05, **P<0.01, ***P<0.001, unpaired Student‘s t-test. (m) Percentage rate increases over baseline in in vivo telemetry ECG recording with peak activity (data calculated from l). (n) In vivo heart rate response to ISO stimulation was reduced by DN-MCU expression in DN-MCU mice, n=11–28 per group. Error bars indicate s.e.m. *P<0.05, **P<0.01, ***P<0.001, unpaired Student‘s t-test. (o) Percentage rate increases over baseline after ISO in in vivo telemetry ECG recording with ISO (data calculated from n).
