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. 2021 Apr 1;131(7):e137752. doi: 10.1172/JCI137752

Figure 10. Identification and regulation of Cx43 hemichannels in nonfailing and failing human ventricular cardiomyocytes.

Figure 10

(A) Unitary current example traces during first and second caffeine applications, NCX current subtracted. Recorded in nonfailing left ventricular human cardiomyocyte. (B) Summary dot plot and transition histogram indicating significantly reduced unitary current event probability during the second caffeine pulse (red) compared with the first (black) (nested t test; N/nNF = 20/64). (C) IV plots depicting linear current-voltage relationship with slope conductance approximately 220 pS and Erev ≈ 0 mV (NNF/nNF = 4/14). (D) Ca2+ release–induced unitary current example traces following 0.5 and 2 Hz pacing in nonfailing and failing human cardiac myocytes (NCX currents subtracted). (E) Summary graph and transition histograms indicate significant increase in unitary current event probability with increasing pacing frequency (nested t test; N/nNF = 5/25, N/nHF = 5/25). This effect is significantly stronger at 2 Hz in failing compared with nonfailing cardiomyocytes (nested t test). (F) Ca2+ release–induced unitary current example traces in the absence and presence of isoproterenol (10 nmol/L) in nonfailing and failing human cardiac myocytes (NCX currents subtracted). (G) Summary graph and transition histograms indicate significant increase in unitary current event probability with isoproterenol compared with baseline (nested t test; N/nNF = 5/13, N/nHF = 5/14). The effect was significantly stronger with ISO in failing compared with nonfailing cardiomyocytes (nested t test). (H) Ca2+ release–induced unitary current example traces during fast pacing and adrenergic stimulation in nonfailing and failing human cardiomyocytes. Including Gap19 in the pipette solution abolished unitary current activity (NCX currents subtracted). (I) Summary dot plot and transition histogram illustrating increased event probability in failing compared with nonfailing myocytes. Gap19 significantly reduced event probability in nonfailing and failing cardiomyocytes (nested 1-way ANOVA; N/nNF = 4/15, N/nHF = 5/15).