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. 2019 Mar 21;8:e41814. doi: 10.7554/eLife.41814

Figure 2. Calcium current blockade dramatically shortened the AP in Tbx5fl/fl;R26CreERT2 atrial cardiomyocytes, consistent with the [Ca]i dependence of AP prolongation following TBX5 loss.

(A) Representative recording of an AP from R26CreERT2 atrial cardiomyocytes before and after 30 µM nifedipine treatment. (B) Representative recording of a Tbx5fl/fl;R26CreERT2 atrial cardiomyocytes before and after nifedipine treatment. (C) Paired APD properties before and after treatment with 30 µM nifedipine (myocytes/mice; n = 8/3Tbx5fl/fl;R26CreERT2 and n = 6/4 R26CreERT2). In R26CreERT2 cardiomyocytes, the effect of nifedipine on APD90 was small, but significant 19 ± 4%. A much larger nifedipine effect was observed in Tbx5fl/fl;R26CreERT2 cardiomyocytes. APD50 decreased by 16 ± 6% and APD90 decreased by 61 ± 6% in the presence of nifedipine. (D) Western blot of atrial tissue in five animals for each genotype showed protein expression for the alpha 1C subunit of the L-type calcium channel (Cav1.2) was unchanged. (normalized to GAPDH) (E,F) Representative ICaL recordings show Peak L-type calcium current was increased in Tbx5fl/fl;R26CreERT2 cardiomyocytes compared to R26CreERT2 (G) Average IV relationship of L-type calcium current (myocytes/mice; n = 22/7 R26CreERT2 and 20/5 Tbx5fl/fl;R26CreERT2). (***p<0.001, **, p<0.01, *, p≤0.05).

Figure 2—source data 1. AP and ICaL parameters for Figure 2C,G.
elife-41814-fig2-data1.xlsx (26.6KB, xlsx)
DOI: 10.7554/eLife.41814.010
Figure 2—source data 2. Western blot for Figure 2D.
elife-41814-fig2-data2.xlsx (8.2KB, xlsx)
DOI: 10.7554/eLife.41814.011

Figure 2.

Figure 2—figure supplement 1. 30 µM Nifedipine blocks L-type calcium current and calcium-induced calcium release in R26CreERT2 and Tbx5fl/fl;R26CreERT2 cardiomyocytes.

Figure 2—figure supplement 1.

Figure 2—figure supplement 2. Steady state inactivation of ICaL was unchanged in Tbx5fl/fl;R26CreERT2 atrial cardiomyocytes.

Figure 2—figure supplement 2.

(A) Protocol used to assess steady state inactivation of ICaL (representative trace from Tbx5fl/fl;R26CreERT2 cardiomyocytes) (B) Steady state inactivation of ICaL was the same in R26CreERT2 and Tbx5fl/fl;R26CreERT2 cardiomyocytes. (myocytes/mice; Representative of 4/9 R26CreERT2 and 3/10 Tbx5fl/fl;R26CreERT2).
Figure 2—figure supplement 2—source data 1. ICaL parameters for Figure 2—figure supplement 2B.
elife-41814-fig2-figsupp2-data1.xlsx (11.6KB, xlsx)
DOI: 10.7554/eLife.41814.009