Browsing by Author "Nakano, Atsushi"

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    The three-dimensional structure of vascular smooth muscle cells: a confocal laser microscopic study of rabbit mesenteric arterioles.
    (2007-06) Nakano, Atsushi; Minamiyama, Motomu; Seki, Junji
    Background: Information of the three dimensional (3D) structure of vascular smooth muscle cells (VSMCs) is essential for understanding the regulatory mechanism of blood flow in the microvascular system. objective: To examine the 3D structure of individual VSMCs in rabbit mesenteric arterioles, using confocal laser scanning microscopy. Methods: Japanese white rabbits were anesthetized with urethane and α-chlorase. After intravital observation of the mesenteric microcirculation under a videomicroscope, the intestine with mesentery was extracted and perfused and fixed with paraformaldehyde under a static pressure (100 mmHg). A section of the mesentery was isolated from the intestine and spread out to simulate the in vivo geometry of the the vascular network. The mesenteric section was stained with fluorescein anti-smooth muscle myosin antibody and rhodamine-labeled anti-rabbit Ig antibody. The samples were observed using confocal laser microscopy, and the 3D images were reconstructed by means of sliced images. The cross-sectional image was re-sliced to measure two axes of the best-fitting ellipse. Single VSMCs were picked out from the vascular wall using the continuity law of density distribution of vessel wall. Results: The cross-sectional shapes of arterioles were not circular but elliptical. The aspect ratio (major to minor axis) of the best-fitting ellipse was in the range from 0.3 to 0.7 for 28 arterioles (diameters: 10-30 μm). On the 3D image of VSMCs, the cell width ranged from 2.2 to 4.5 μm. The cells were classified into round and spindle types. The cell width of round shape was significantly larger than that of spindle shape. The VSMCs appeared to arrange circumferentially and tightly along the cross-section along the axis of vessel. The mean length of single VSMCs was approximately 1.2 times of the circumferential length of the arteriole. This cellular arrangement may have influence on the distribution of mechanical stress by VSMC-induced myogenic force. Conclusion: Confocal laser microscopy is useful for quantitative analysis of the 3D arrangement of individual VSHCs.