ELIMINATION OF TRITIUM-LABELED HYALURONIC-ACID FROM NORMAL AND OSTEOARTHRITIC RABBIT KNEE JOINTS

The half-life of [H-3]hyaluronic acid in rabbit knee joints was estima ted using two methods: (i) by following the [H-3]hyaluronan content of the synovial fluid after intra-articular injection and (ii) by follow ing the (H2O)-H-3 radioactivity of plasma after intra-articular inject ion of [H-3]hyaluronan. For normal rabbits we obtained a half-life of 15.8 hours (method I) and 17.5 +/- 1.0 hours (mean +/- SEM, method II) , respectively. The second method was used to estimate the kinetics of the hyaluronan elimination from normal, sham-operated, as well as fro m osteoarthritic rabbit knee joints (Colombo model of osteoarthritis). Four weeks after injury, during the developing phase of osteoarthriti s, the half-life of hyaluronan rose significantly to 23.5 +/- 2.1 hour s and returned to normal levels (17.4 +/- 2.7 hours) 12 weeks after th e operation (osteoarthritis developed). At the stage of developed oste oarthritis, the clearance rates were considerably higher than in norma l rabbits.