Figure 4. Effect of pulsating fluid flow on NO production by TNF--treated periosteal fibroblasts, osteoblasts, and osteocytes. (A) Cumulative NO production during 30 min of PFF treatment or under static conditions. (B) NO production expressed as PFF-treated-over-control ratios (± PFF) at 10 and 30 min. Application of PFF increased NO production at 30 min in TNF--treated osteocytes, but not in osteoblasts and periosteal fibroblasts. Values are obtained from 4-5 glass slides from 2 experiments (mean ± SEM). Dashed line, ± PFF = 1 (no effect). PFF, pulsating fluid flow; Stat, static cultures; PF, periosteal fibroblasts; OB, osteoblasts; OCY, osteocytes. *Significant effect of PFF, p < 0.05.