Calcium Regulation on the Atrial Regional Difference of Collagen Production Activity in Atrial Fibrogenesis

Figures

• 

  Figure 1. Ca2+ entry in the isolated passage 0 (P0) left atrium (LA) and right atrium (RA) fibroblasts from healthy rats. Left panels represent intracellular Ca2+ tracing from the LA fibroblasts (upper tracing, n = 18 LA fibroblasts from four rats) and RA fibroblasts (lower tracing, n = 17 RA fibroblasts from four rats). The cells were first incubated with a Ca2+-free extracellular solution to deplete the Ca2+ stores. Ca2+ entry was induced after increasing extracellular Ca2+ to 10 mmol/L. Right panels show the change in intracellular Ca2+ from a Ca2+-free solution to a 10 mmol/L Ca2+ solution (∆F340/F380). *** p < 0.005.

• 

  Figure 2. Membrane gadolinium (Gd3+)-sensitive currents in isolated passage 0 (P0) left atrium (LA) and right atrium (RA) fibroblasts from healthy rats. Left panels reveal tracings of the Gd3+ (100 μmol/L)-sensitive non-selective cation current from LA fibroblasts (n = 10 from five rats) and RA fibroblasts (n = 10 from five rats). Right panels reveal the current/voltage (I/V) relationship of the Gd3+-sensitive non-selective cation current. * p < 0.05, ** p < 0.01, *** p < 0.005. The insets in the current traces show the various clamp protocols.

• 

  Figure 3. Ca2+ entry on the diversity of the collagen production ability in the cultured passage 1 (P1) left atrium (LA) and right atrium (RA) fibroblasts from healthy rats. Photographs and averaged data of the pro-collagen type I (n = 6 independent experiments), pro-collagen type III (n = 6 independent experiments) and phosphorylated Ca2+/calmodulin-dependent protein kinase II (pCaMKII, n = 6 independent experiments) expression in LA and RA fibroblasts with or without 1 mmol/L ethylene glycol tetra-acetic acid (EGTA, an extracellular Ca2+ chelator) for 48 h. GAPDH was used as a loading control. * p < 0.05, *** p < 0.005.

• 

  Figure 4. Ca2+ signaling pathway on the diversity of the collagen production capability between the cultured passage 1 (P1) left atrial (LA) and right atrial (RA) fibroblasts from healthy rats. (A) Photographs and averaged data of the phosphorylated phospholipase C (pPLC, n = 5 independent experiments), stromal interaction molecule 1 (STIM1, n = 5 independent experiments) and Orai (n = 5 independent experiments) expression of LA and RA fibroblasts. (B) Photographs and averaged data of the transient receptor potential canonical (TRPC) 3 (TRPC3, n = 5 independent experiments) and TRPC6 (n = 5 independent experiments) expression of LA and RA fibroblasts. (C) Photographs and averaged data of the pro-collagen type I (n = 5 independent experiments) and pro-collagen type III (n = 5 independent experiments) expression of LA and RA fibroblasts with or without a Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor (KN93, 10 μmol/L) for 48 h. GAPDH was used as a loading control. * p < 0.05, ** p < 0.01, *** p < 0.005.

• 

  Figure 5. Membrane gadolinium (Gd3+)-sensitive currents in isolated passage 0 (P0) left atrium (LA) and right atrium (RA) fibroblasts from heart failure (HF) rats. Left panels reveal tracings of the Gd3+ (100 μmol/L)-sensitive non-selective cation current from HF LA fibroblasts (n = 10 from six rats), HF RA fibroblasts (n = 10 from five rats). Right panels reveal the current/voltage (I/V) relationship of the Gd3+-sensitive non-selective cation current. * p < 0.05, ** p < 0.01, *** p < 0.005. The insets in the current traces show the various clamp protocols.

• 

  Figure 6. Illustration of the proposed mechanism that contributes to the differential collagen production in left atrium (LA) and right atrium (RA) fibroblasts. The diversities of the phosphorylated phospholipase C (pPLC) signaling and the expression of transient receptor potential canonical (TRPC) 3 Ca2+ channels activate different levels of Ca2+ influx, which may induce a different phosphorylated Ca2+/calmodulin-dependent protein kinase II (CaMKII) expression and collagen production between LA and RA fibroblasts. The different levels of stromal interaction molecule 1(STIM1) in LA and RA fibroblasts may also contribute to the diversity of collagen production via the activation of the Orai channel. IP3: Inositol trisphosphate.