Substrate Deformation Levels Associated With Routine Physical Activity Are Less Stimulatory to Bone Cells Relative to Loading-Induced Oscillatory Fluid Flow

Although it is well accepted that bone tissue metabolism is regulated by external mechanical loads, it remains unclear to what load-induced physical signals bone cells respond. In this study, a novel computer-controlled stretch device and parallel plate flow chamber were employed to investigate cytosolic calcium Ca2+i mobilization in response to a range of dynamic substrate strain levels (0.1–10 percent, 1 Hz) and oscillating fluid flow (2 N/m2, 1 Hz). In addition, we quantified the effect of dynamic substrate strain and oscillating fluid flow on the expression of mRNA for the bone matrix protein osteopontin (OPN). Our data demonstrate that continuum strain levels observed for routine physical activities (