BK Channels Orchestrate Cardiac Homeostasis Through Mitochondrial Uncoupling Proteins

Figures

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  Figure. 1.. The absence of BK causes cardiac hypertrophy and dysfunction. A. Masson trichrome staining. There is a significantly increased collagen deposition (blue) in KO mice heart. B. and C. Total perimeter and frequency of cardiomyocytes. D. Echocardiography showing PSLAX view of wt and KO hearts. E. F. G. Wall thickness measured from D. and H. H. M-mode Echocardiography traces in adult wt and KO mice, respectively. I. Comparison of LVEF of wt and KO mice, n=5, p< 0.01. F J. Comparison of FS of wt and KO mice, n=5, *, p<0.01. K. Strain analysis of WT & KO hearts. L. Quantification of global longitudinal strain of wt and KO mice, n=5, *, p<0.01. M and N. Color Doppler and region of pulse wave Doppler interrogation. Tissue Doppler to derive Tei index. P. Comparison of E/A peak early to a late diastolic mitral inflow velocity ratio of WT and KO, n=5, *, p<0.05. Q. E/E′ peak early diastolic mitral inflow velocity to tissue Doppler mitral annular velocity ratio of WT and KO, n=5, *, p<0.05.

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  Fig. 2.. Ablation of BK decreases the aortic flow. A and F, Color Doppler of ascending and descending aorta, B, D, G and I, shows region of pulse wave Doppler interrogation; C and E, pulse wave Doppler flow velocities of the ascending and descending aorta in wt mice. H and J, pulse wave Doppler flow velocities of the ascending and descending aorta in Kcnma1−/−. K. Schematic of aorta, red arrows indicate position of the probe. L and M. Comparison of VTI and peak velocities of wt and Kcnma1−/−. n=3, *,p< 0.05

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  Fig. 3.. Ablation of BK causes a change in cardiac dysfunction pathways. A. Pie chart representing various cardiac dysfunction pathways. Numbers represent a percentage. B. Genes involved in cardiac dysfunction showed a change in expression in Kcnma1−/− cardiomyocytes. C. UCP1,2,3 were down-regulated in Kcnma1−/−. D. Quantification of UCP1, 2 & 3 mRNA. E. Western blot show down regulation of UCP1 (5 fold), and 3 (1.5 fold). F. Decrease in levels of UCP2 (2 fold) in Kcnma1−/−. GAPDH and Ponceaus S are controls. G. Quantification of F.

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  Fig. 4.. Pharmacological overexpression of UCPs improves cardiac function. A. CL316,243 compound (i.p. 1mg/kg) weekly for four weeks increased the LVEF of BK KO mice (green) but not of mice injected with saline (purple). WT mice injected with CL316,243 (red) or saline (blue) showed no difference in ejection fraction. Our preliminary data indicate that CL316,243 specifically improved the LVEF of KO hearts. There was a small but insignificant improvement in WT (light blue). N=4 in all groups. B. Cardiac lysates of Kcnma1−/− mice from A (with and without CL compound after week 4) were probed for expression of PGC-1α, pFoxo3a and Foxo3a. Expression of PGC-1α and pFoxo3a increases but Foxo3a does not show any significant change in expression. C. Quantification of UCP1, 2 and 3 expression from B and normalized to Ponceau-S stained membrane. D. Western blot shows a significant reduction in the expression of PGC-1α and pFoxo3a in BK knockout animals but increase in the expression of Foxo3a levels. Quantification is provided for PGC-1α in E, pFoxo3a in G and Foxo3a in F.