Carbon Dioxide and the Utilization of Oxygen

Abstract

Carbon dioxide and hydrogen ions may act on the utilization of oxygen at different levels of integration. The lowest level of integration is represented by the chemical reactions. From the papers presented earlier it seems likely that many metabolic reactions depend on pH, e.g. all reactions where NAD is involved. A somewhat higher level of integration, though closely related to the level of chemical reactions, is represented by carbon dioxide effects on the oxygen dissociation curve. A still higher level of integration with respect to the effects of carbon dioxide are reactions of organs and organ systems as, for instance, the stimulatory effect of carbon dioxide on the respiration or on the cerebral blood flow. Such reactions affect profoundly the supply of oxygen to the different organs. As a consequence of the aforementioned effects of carbon dioxide, the utilization of oxygen and the oxygen consumption of the whole organism could well be altered by carbon dioxide. In this paper, examples for the effects of carbon dioxide at different levels of integration will be discussed. Furthermore, I shall attempt to reduce these effects to a common denominator by defining a quantitative index of oxygen utilization.