Nitric Oxide Response to Shear Stress by Human Bone Cell Cultures Is Endothelial Nitric Oxide Synthase Dependent

• Published in: Biochemical and biophysical research communications Vol. 250; no. 1; pp. 108 - 114
• Main Authors: Klein-Nulend, J., Helfrich, M.H., Sterck, J.G.H., MacPherson, H., Joldersma, M., Ralston, S.H., Semeins, C.M., Burger, E.H.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 08.09.1998
• Subjects: Adaptation, Physiological; Adolescent; Adult; Aged; Aged, 80 and over; Base Sequence; Bone and Bones - cytology; Bone and Bones - metabolism; Bone and Bones - physiology; bone cells; Cells, Cultured; Child; DNA Primers; ecNOS; fluid shear stress; Humans; mechanical stress; Middle Aged; nitric oxide; Nitric Oxide - metabolism; nitric oxide synthase; Nitric Oxide Synthase - genetics; Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type III; Physical Stimulation; Polymerase Chain Reaction; RNA, Messenger - genetics; Stress, Physiological - enzymology; Stress, Physiological - metabolism; bone cells; mechanical stress; ecNOS; nitric oxide; nitric oxide synthase; fluid shear stress
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.1998.9270

Bone cells, in particular osteocytes, are extremely sensitive to shear stress, a phenomenon that may be related to mechanical adaptation of bone. In this study we examined whether human primary bone cells produce NO in response to fluid shear stress and established by RT/PCR which NOS isoforms were expressed before and after application of shear stress. One hour pulsating fluid flow (PFF; 0.7 ± 0.02 Pa, 5 Hz) caused a rapid (within 5 min) 2 to 4-fold increase in NO production. NO release was only transiently increased during the first 15 min of exposure to PFF, and remained at control levels during a 1-24 hr postincubation period. In both control and PFF-treated cells, mRNA was easily detected for ecNOS, but not nNOS, and only minimal amounts iNOS were found. mRNA levels for ecNOS increased 2-fold at 1 hr after 1 hr PFF treatment. These results suggest that the rapid production of NO by human bone cells in response to fluid flow results from activation of ecNOS. PFF also leads to an increase in ecNOS mRNA which is likely related to the shear stress responsive element in the promoter of ecNOS.