Effects of Dissolved Carbon Monoxide on the Respiratory Activity of Perfused Neuronal and Muscle Cell Cultures

Abstract

In order to address the question of whether small amounts of dissolved CO may inhibit cellular respiration, cultured mouse neuroblastoma cells and primary cultures of chick neurons, rat astrocytes and chick skeletal muscle and heart cells were exposed to CO containing buffer solutions in a closed perfusion system. Oxygen uptake was measured simultaneously with two polarographic oxygen electrodes as the difference in partial pressure of oxygen between the inlet and outlet of the perfusion chamber. After registration of the basal respiratory activity, perfusion solutions containing 5 ul O₂/ml were bubbled with CO or N₂ at a rate of 200 ml/min for 120 sec. By this procedure the partial pressure of O₂ was decreased to reach a value of about 50% of the initial O₂ content for both gases. Perfusion was then continued for 30 min at a rate of 0.5 ml/min. The respiratory activity of all the perfused cell cultures, except chick neurons, was found to be inhibited (13-29%) by perfusion solutions bubbled for 120 sec with CO as compared to N₂ controls. Of the cells from the nervous system, astrocytes were more sensitive than neurons. Apparently, small amounts of dissolved CO can inhibit cellular respiration in the presence of a physiologically adequate amount of oxygen.