Heterogeneity of ventricular action potentials in neonatal rat cardiomyocytes and methodological aspects of patch clamp measurements

Figures

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  FIGURE 1. AP heterogeneity in NRVCM. Depicted are averaged traces of all analyzed APs of NRVCM [(A), black] and APs in NRVCM from the analyzed literature [(A), grey]. Mean values of APD90, APD50, APA and RMP from analyzed data [(B), black circles] and literature [(B), grey crosses] are shown.

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  FIGURE 2. Temperature dependency in NRVCM-APs. Depicted are mean APD90 at different assay temperature [(A), grey crosses: data from analyzed literature, black circles: original data]. Original data (B) showed no significant difference for APD90, APD50, APD30 and APA. A significant decrease was found for dV/dt in between 37°C and 28°C. data presented as mean + SEM, **: p < 0.01 (Mann-Whitney U test).

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  FIGURE 3. HMP/RMP dependency in NRVCM-APs Mean APD90 (orange) and APD50 (blue) with corresponding RMP/HMP are shown in (A) (crosses: literature data, circles: own data). Mean APD90, APD50, APD30, APA, and dV/dt with SEM of NRVCM (n = 7) are shown at different HMPs (B). Exemplary AP-traces of the same neonatal rat ventricular cardiomyocyte at different HMP are shown with variable scale of the time-axis to illustrate early AP phases (C) and the whole AP (D). *: p < 0.05, **: p < 0.01 (repeated measures ANOVA).

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  FIGURE 4. Induction energy dependency in NRVCM-AP. Mean APD90, APD50, APD30, APA, dV/dt with SEM close to the individual cells’ threshold (1.0-fold) and at 1.5-, 2.0-, 3.0- and 5.0-fold the threshold, are illustrated (A). *: p < 0.05, n = 7. Exemplary AP traces are shown (B). APD90 calculated at threshold energy level (black line) and at +400% (green line), are depicted. The timepoint at maximal AP amplitude for each trace is set to 0 ms. Corresponding rectangular induction current pulses are depicted in panel (C). Statistical comparison in (A) with repeated measures ANOVA as main test, corrected for multiple comparisons with Dunnett’s test, +0% threshold as control column. n = 7. *: p < 0.05, **: p < 0.01.

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  FIGURE 5. Dependency of NRVCM-AP to induction repetition and assay duration Mean APD90 of NRVCMs at 15 repetitive inductions (at 1 Hz stimulation frequency) are shown with SEM (A). Exemplary traces (sweep 1 black, sweep 2 red, sweep 3 blue, sweep 4–15 grey) are depicted (B). Mean APD90 (black) of NRVCM with AP-induction every 3 min over a timespan of 21 min (n = 23) and each cells individual data (grey) are shown (C). Exemplary APs are shown (first AP black, increasingly brightening over the consecutive APs) in (D) *: p < 0.05, **: p < 0.01 (repeated measures ANOVA, corrected for multiple comparisons with Dunnett’s test, first AP as control).