Venous ligation-mediated bone adaptation is NOS 3 dependent.

Area of Science:

• Bone biology
• Mechanobiology
• Physiology

Background:

• Interstitial fluid flow (IFF) is a proposed mechanism for bone modeling independent of mechanical strain.
• Nitric oxide (NO) is implicated in mediating IFF's effects on bone.
• The precise role of NO in IFF-mediated bone adaptation requires further elucidation.

Purpose of the Study:

• To investigate the role of nitric oxide synthase 3 (NOS 3) in IFF-mediated bone adaptation.
• To determine if IFF protects against bone loss and if this effect is NO-dependent.

Main Methods:

• Utilized wild-type (WT) and NOS 3 knockout (KO) mice.
• Induced altered IFF via femoral vein ligation in one limb; sham operation in the contralateral limb.
• Applied hindlimb suspension to induce bone loss, uncoupling limb IFF from mechanical loading.

Main Results:

• Hindlimb suspension caused bone loss in both WT and NOS 3 KO mice.
• Venous ligation protected against bone loss in WT mice (p<0.05), a significant difference compared to sham.
• This protective effect of venous ligation was abolished in NOS 3 KO mice, indicating NO dependence.
• Mechanical testing revealed higher bone strength in ligated limbs of WT mice, but not in NOS 3 KO mice.

Conclusions:

• IFF can modulate bone modeling and offers protection against bone loss.
• The bone-protective effects of IFF are dependent on NOS 3 and nitric oxide.
• These findings support IFF as a significant factor in bone adaptation, mediated by NO.