Atrial natriuretic Peptide expression in human articular cartilage.

This immunohistochemical study aims to investigate the Atrial natriuretic peptide (ANP)-presence and localization in human articular cartilage. Fragments of articular cartilage covering the femoral head were removed from patients submitted to surgical operation after femoral neck fracture without joint disease. The samples were immunostained with anti-ANP antibody. The results demonstrate that ANP is present in chondrocytes in all the three zones of the articular cartilage. Superficial chondrocytes show strong ANP-immunopositivty. The presence of ANP in the articular cartilage suggests that ANP may play a role in cartilage metabolism by regulating transport of molecules through the different zones of the articular cartilage and in maintenance of its homeostasis; probably ANP could be also involved in the regulation of the balance between synovial fluid and the other body fluids.