PULSATING FLUID-FLOW INCREASES PROSTAGLANDIN PRODUCTION BY CULTURED CHICKEN OSTEOCYTES - A CYTOSKELETON-DEPENDENT PROCESS

It has been postulated that the transduction of mechanical stress sign als to bone cells occurs via loading-dependent how of interstitial flu id through the lacuno-canalicular network of bone. We have shown earli er that chicken osteocytes release enhanced amounts of prostaglandin E (2) after 1 h treatment with pulsating fluid flow (PFF, 0.5+/-0.02 Pa, 5 Hz). Here we study the acute response to PFF on three cell populati ons derived from fetal chick calvariae, namely periosteal fibroblasts (PF), an osteoblast and osteocyte containing population (OBmix), and o steocytes (OCY), and the involvement of the actin-cytoskeleton in this process, All three cell populations rapidly (OCY: within 5 min, OBmix , PF: within 10 min) increased their release of prostaglandins E(2) an d I-2 in response to PFF, but the response by OCY was 2-4 times higher than that by OBmix or PF. Disruption of the actin-cytoskeleton by cyt ochalasin B completely abolished the response. We conclude that osteoc ytes are more sensitive to fluid shear stress than immature bone cells , and that the actin-cytoskeleton is involved in the response to fluid flow. (C) 1996 Academic Press, Inc.