OXYGEN-CONSUMPTION OF CALVARIAL BONE-CELLS IN-VITRO

Tissues with tortuous and narrow diffusion path ways and cells that ar e remote from blood vessels nonetheless can show high metabolic activi ty of which the underlying bases (transport mechanisms) are not fully understood. In one such bone tissue, the O-2 consumption was measured bq analyzing the decrease in the partial pressure of oxygen (PO2) in a closed chamber containing calvarial fragments from adult guinea pigs (250-400 g) or from neonatal rats and guinea pigs, The O-2, consumptio n of fragments from adult guinea pigs amounted to 0.05, 0.066, and 0.0 95 ml/100 g: minute at 24, 27, and 36.5 degrees C, respectively. When the temperature exceeded 43 degrees C, O-2 consumption irreversibly s topped. Both antimycin A anti rotenone, which block the respiratory ch ain, reduced O-2 consumption to approximately 20% of control values. O -2 consumption was significantly higher in neonatal animals (0.369 ml/ 100 g minute at 27 degrees C) and could be blocked completely by ant imycin A. On the basis of the high consumption of O-2 by bone cells, N c hypothesize that specialized transport systems, i,e., gap junctions, are required to provide a sufficient supply of nutrients to cells in osseous tissue.