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Determining the Influence of Hydrostatic Pressure on the Proliferation of Primary Rat Osteoblast 2,3V. Slater, 1,4E. A..C. Almeida, 1K. Calero, 1,4R. K. Globus, 1W.  and 1N.D. Searby,   1NASA Ames Research Center, Moffett Field, CA. 2Oregon State University, Corvallis OR. 3NASA Ames Academy, and 4University of California San Francisco

   In previous studies we found that hypergravity stimulation of fetal rat calvarial osteoblasts increased cell proliferation, prostaglandin E2 (PGE2) release, and  focal adhesion formation, as well as decreased microtubule network height.  One component of mechanical loading provided by centrifugation to generate hypergravity is increased hydrostatic pressure due to the increased gravity acting on the column of fluid above the adherent cell layer.  This study seeks to determine if increased hydrostatic pressure alone can cause the same changes in osteoblasts as those produced by hypergravity.  To conduct these studies we developed a cell culture pressure chamber (CCPC).  The CCPC allows for the study the affects of hydrostatic pressure without the associated component of gravity.  Primary fetal rat osteoblasts grown for  3 days after isolation, cells were placed at 20% confluence on collagen-coated plates. Cells were allowed to attach for 30 min, then were subjected to 17-g  or the equivalent 2.x kPa hydrostatic pressure for 24 hr, then compared to controls.  Preliminary results suggest that the same magnitude increased proliferation observed under hypergravity can also be induced by hydrostatic pressure alone.  Understanding the importance of the hydrostatic loading component to the hypergravity response will improve our understanding of fundamental cell biology responses to gravity, and may suggest possible mechanical or pharmaceutical countermeasures to the problems of bone loss in space.

Supported by NASA Ames DDF to NDS and NASA 00-OBPR-01-066