Search

We proposed a mathematical model for the microdynamics of cultured cells measured with ECIS (Electrical Cell-substrate Impedance Sensing) system that can separately evaluate cell-to-cell and cell-to-substrate gaps. Our mathematical model is composed of culture medium impedance between cells (Zsol), cell impedance (Zc), and polarization impedance of the electrode (Zp). Zsol consists of the resistance between cells (Rsol) and the capacitance between cells (Csol) of the culture medium. In particular, Rsol is the resistance component related to the cell-to-cell distance (A). Zc consists of capacitance of the cell membrane (Cc) and resistance of the cell membrane (Rc). Zp depends on the cell-to-substrate distance (h) because of the shielding effect of cells to the electrode. The shielding effect is defined as shielding coefficient (Sk). We examined the changes in the impedance of the electrode without or with cells in various conditions. The electrical characteristics of the electrode with or without cells agreed well with those measured in ECIS system. It was found that whether A or h caused the changes in the impedance could be determined based on the changes in the total resistance and reactance (capacitance); A mainly affects the total resistance value, and h mainly affects total capacitance value. Therefore, we can simply estimate the changes in cell-to-cell and cell-to-substrate gaps with measured total resistance and reactance (capacitance). Based on these results, when the cultured endothelial cells (HUVEC) were stimulated with estrogen for 40 hours, it was proved that the cell-to-cell distances decreased, even though the cell-to-electrode distances slightly increased. This result suggests that the barrier function of endothelium is fortified by estrogen.

The recently proposed Physiome is considered as a powerful successor to the Genome. The definition of Physiome is the quantitative description of the physiological dynamics or functions of the intact organism. The physiome includes integration of knowledge through functional modules of hierarchical system elements of biological systems, and modeling. Biomechanics will offer potent tools to promote the Physiome. By using modern microvisualization technology with physiomic model, this manuscript introduces our physiomic approach to coronary microcirculation which supplies oxygen and nutrients to heart muscles; 1. Mechanical interaction between coronary blood flow and cardiac contraction, and 2. Capillary network and its function.

We have aimed to assess total Ca 2+ handling in excitation-contraction coupling in a beating left ventricle (LV). Our newly developed integrative analysis method utilizes the internal Ca 2+ recirculation fraction (RF), O2 consumption ( Vo 2) for Ca2+ handling, and O 2 cost of Emax (contractility index) of the LV. We have obtained the O 2 cost of Emax from Vo 2 measured at different contractility levels, and have combined the cost with RF calculated from the beat-constant of the exponential decay component of the postextrasystolic potentiation. Our method calculates the unknown total Ca2+ handling from the RF and the " Ca 2+ handling Vo 2". The calculated total Ca 2+ handling fell between 30 and 110 μmol/kg, depending on contractility and pathological conditions. The present method also enable's reasonable assessment of futile Ca 2+ cycling and of the Ca 2+ reactivity of Emax. Our method seems useful to better understanding of the pathophysiology of total Ca 2+ handling in a beating heart.