Probing softness of the parietal pleural surface at the micron scale

JOURNAL OF BIOMECHANICS

卷:44

Article

Kim, Jae Hun¹  Butler, James P.^1,2,3,4  Loring, Stephen H.¹ 

[1] Beth Israel Deaconess Med Ctr, Dept Anesthesia Crit Care & Pain Med, Boston, MA 02215 USA

[2] Harvard Univ, Sch Med, Dept Med, Div Sleep Med, Boston, MA 02215 USA

[3] Harvard Univ, Sch Publ Hlth, Boston, MA 02115 USA

[4] Brigham & Womens Hosp, Boston, MA 02115 USA

关键词: Parietal pleura;    AFM;    Hertzian indentation;    Elastohydrodynamic lubrication;    Rat;   

DOI  :  10.1016/j.jbiomech.2011.07.008

来源: Elsevier

【 摘 要 】

The pleural surfaces of the chest wall and lung slide against each other, lubricated by pleural fluid. During sliding motion of soft tissues, shear induced hydrodynamic pressure deforms the surfaces, promoting uniformity of the fluid layer thickness, thereby reducing friction. To assess pleural deformability at length scales comparable to pleural fluid thickness, we measured the modulus of the parietal pleura of rat chest wall using atomic force microscopy (AFM) to indent the pleural surface with spheres (radius 2.5 and 5 mu m). The pleura exhibited two distinct indentation responses depending on location, reflecting either homogeneous or significantly heterogeneous tissue properties. We found an elastic modulus of 0.38-0.95 kPa, lower than the values measured using flat-ended cylinders > 100 mu m radii (Gouldstone et al., 2003. Journal of Applied Physiology 95, 2345-2349). Interestingly, the pleura exhibited a three-fold higher modulus when probed using 2.5 vs. 5 pm spherical tips at the same normalized depth, confirming depth dependent inhomogeneous elastic properties. The observed softness of the pleura supports the hypothesis that unevenness of the pleural surface on this scale is smoothed by local hydrodynamic pressure. (C) 2011 Elsevier Ltd. All rights reserved.

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