Experimental osteoarthritis in the rabbit. III. Acute osteoarthritis: subchondral P02 and oxygen consumption and diffusion capacity in the synovial membrane

The effects of reduced oxygen tension on cell proliferation and matrix synthesis in synovium and tendon explants from the rabbit carpal tunnel: an experimental study in vitro

Local ischemia may play an important role in the development of tendon degeneration as well as entrapment neuropathies. In order to investigate the cellular effects of hypoxia on tendon and synovial tissue from the carpal canal, dose response effects of oxygen on cell proliferation and synthesis of matrix components were examined in segments of synovial and flexor digitorum profundus tendon from the carpal tunnel of rabbits during short term culture. Explants were incubated in airtight containers flushed with either 0%, 1%, 3%, 20% O2 plus 2% CO2 and N2 to balance and labeled with either 3H-thymidine or 3H-proline and 35S-sulfate. Cell proliferation was significantly inhibited by hypoxia in synovium but not in tendon (P = 0.03). In parallel, the synthesis of non-collagenous proteins was significantly reduced in synovium but not in tendon (P = 0.006). In both tissues hypoxia significantly inhibited collagen synthesis. On the other hand, hypoxia had no significant effect on the synthesis of new proteoglycans as determined by 35S-sulfate incorporation. Hypoxia can inhibit cell proliferation and alter synthesis of matrix components in synovial tissue, but may only have minor effects on non-collagen protein synthesis in tendon explants from the carpal canal of rabbit forepaws.

Partial pressures of oxygen and carbon dioxide in bone and their correlation with bone-blood flow: effect of decreased arterial supply and venous congestion on intraosseous oxygen and carbon dioxide in an animal model

Pathological changes in bone have been related to a preceding impediment of the arterial or venous bone circulation and hypoxia. In this study, we analyzed the feasibility of mass spectrometry in measuring intraosseous oxygen and carbon dioxide. The partial pressures were also measured in intraosseous blood samples, and blood flow in bone was measured with the radioactive microspheres technique. The average partial pressure of oxygen in the lateral femoral condyle was 34 +/- 1.6 mm Hg when measured in intraosseous blood samples and 36.3 +/- 2.3 mm Hg when measured with the on-line mass spectrometer, with significant correlation between the methods. The absolute value of the partial pressure of carbon dioxide measured in situ with mass spectrometry was correlated with the value in the withdrawn blood. There was no significant difference in partial pressures of oxygen and carbon dioxide between the two sides or between repetitive measurements. Arterial occlusion resulted in severe hypoxia, whereas more moderate changes followed venous occlusion.

Effects of variation in systemic blood pressure on intraosseous pressure, PO2, and PCO2

Several regulatory mechanisms have been shown to influence the intraosseous circulation. The influence of general hypovolemia on bone circulation and possible regulatory effects were investigated by recording the intraosseous pressure and PO2 and PCO2 continuously by mass spectrometry in rabbits. Hypovolemia was induced by repeated bleedings. The intraosseous and arterial pressures were found to be linearly related. The intraosseous PO2 already decreased after the first step of bleeding and decreased more than 50% of the initial value after an average blood loss of 40 ml. The intraosseous PCO2 showed an opposite pattern. The experimental PO2 vs. arterial pressure curves were similar to curves obtained by a computer simulation that assumes the blood flow to be proportional to the intraosseous pressure.

Oxygen consumption, diffusing capacity and blood flow of the synovial membrane in osteoarthritic rabbit knee joints

In osteoarthritis the changes of the synovial membrane may seriously alter the oxygen transfer characteristics from the capillaries of the membrane to the synovial fluid and hence impede or deprive the joint cartilage of its sole source of oxygen. In the present study we have estimated the blood flow (Q), diffusing capacity (DO2) and oxygen consumption (VO2) of the synovial membrane in the chronic non effusive stage of experimental osteoarthritis. In 14 osteoarthritic knee joints we found a statistically significant increase in oxygen consumption, compared to previously reported results from normal joints, whereas the diffusing capacity and the blood flow were unchanged. The implication of this is that the partial pressure difference required to overcome the increased oxygen consumption was increased with a factor 4.3 and that the oxygenation of the joint cartilage was reduced with approx. 30 Torr.

Oxygen consumption, diffusing capacity and blood flow of the synovial membrane in osteoarthritic rabbit knee joints

In osteoarthritis the changes of the synovial membrane may seriously alter the oxygen transfer characteristics from the capillaries of the membrane to the synovial fluid and hence impede or deprive the joint cartilage of its sole source of oxygen. In the present study we have estimated the blood flow (Q), diffusing capacity (DO2) and oxygen consumption (VO2) of the synovial membrane in the chronic non effusive stage of experimental osteoarthritis. In 14 osteoarthritic knee joints we found a statistically significant increase in oxygen consumption, compared to previously reported results from normal joints, whereas the diffusing capacity and the blood flow were unchanged. The implication of this is that the partial pressure difference required to overcome the increased oxygen consumption was increased with a factor 4.3 and that the oxygenation of the joint cartilage was reduced with approx. 30 Torr.

Intracompartmental pressure, PO2, PCO2 and blood flow in the human skeletal muscle

Measurement of PO2, PCO2, and blood flow in skeletal muscle could be a supplement to examination in clinical practice. Mass spectrometry was utilized to measure these parameters in the resting anterior tibial muscle of healthy adults. The partial pressures of oxygen and carbon dioxide were 21 +/- 3.6 and 46 +/- 2.5 Torr, respectively. The intracompartmental pressure was 8 +/- 1.1 Torr. The oxygen tension in muscle varied only slightly when arterial partial pressure was increased. The blood flow (tissue perfusion coefficient) estimated by washout of an inert gas was 5.4 +/- 0.8 ml/100 g/min. The results are in accordance with those from animal studies of skeletal muscle. The study demonstrates the feasibility of measuring PO2, PCO2, and blood flow in skeletal muscle by mass spectrometry.