High hydrostatic pressure induces slow contraction in mouse cardiomyocytes

Figures

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  Figure 1. High hydrostatic pressure induced slow contraction in mouse cardiomyocytes. (A) Cardiomyocyte images and their computed FFT spectrum of sarcomere during the application of the pressure at 20 MPa. The gradual shift of the peak position in the FFT spectrum to higher frequency corresponds to a decrease in the SL. The black inset is magnified in the lower right corner of the image. Scale bar, 20 μm. (B) The time-dependent SL alteration under ambient pressure (0.1 MPa) and high pressure (5, 10, and 20 MPa). The SL gradually declined under pressures of 5, 10, and 20 MPa, while it remained constant under ambient pressure. Each different data point represents the different cells. (C) Comparison of SL under each pressure condition (5, 10, and 20 MPa). Pressures of 5, 10, and 20 MPa (n = 11, 8, and 12 cells, respectively) led to a decrease in SL compared with the ambient pressure of 0.1 MPa (n = 12 cells). ∗∗p < 0.01. Images recorded at 1 frame s−1. Refer to Video S1. Pressure at 0.1 MPa, Video S2. Pressure at 5 MPa, Video S3. Pressure at 10 MPa, Video S4. Pressure at 20 MPa. (D) TEM images of a single cardiomyocyte before and after the application of 20 MPa pressure. The images show that…

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  Figure 2. Effects of myosin ATPase inhibitor (BDM) on the pressure-induced slow contraction. (A) The pressure-induced slow contraction in live cardiomyocytes is observed in normal Tyrode solution during the application of pressure (upper panel), while its slow contraction is not observed in BDM-containing Tyrode solution (lower panel). Images were recorded at 1 frame s−1. Refer to Videos S4 and S6. (B) BDM significantly inhibits the pressure-induced shortening in cells chemically fixed after the pressure treatment (n = 30 cells), while the shortening is still observed in the absence of BDM (n = 30 cells). ∗∗∗p < 0.001.

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  Figure 3. Alteration in intracellular Ca2+ of cardiomyocytes under high-hydrostatic pressure. (A) Sequential grayscale images of Ca2+ fluorescence intensity in cardiomyocytes at 20 MPa pressure; Ca2+ intensity remains constant with time. Scale bars, 10 μm. (B) Time-dependent change of normalized Ca2+ intensity to maximal Ca2+ intensity in cardiomyocytes under each pressure condition (0.1 MPa [n = 4 cells]; 20 MPa [n = 6 cells]). (C) Comparison of Ca2+ intensity between 0.1 and 20 MPa (n = 4 and 6 cells, respectively) at the initial (t = 0 s) and end (t = 30 s) states. N.S., not significant. Images were recorded at 10 frame s−1. Refer to Videos S8 and S9.