Local factors in tissue oxygenation.

Abstract

Oxygen tension varies from tissue to tissue and is maintained in a dynamic equilibrium between oxygen delivery and oxygen uptake. Both of these factors may vary from time to time, and if P02 is measured at a particular point over a period of some hours, slow fluctuations will be observed in most tissues, often with more rapid fluctuations superimposed. A mean level is, however, normally maintained but differs even within a single tissue from place to place. Oxygen uptake reflects local energy requirements and may change relatively slowly in organs such as liver or skin or very rapidly in muscle and brain tissue. To maintain an adequate supply of oxygen to structures with varying requirements there must be an accurate feedback mechanism coupling the need to the delivery system. Local vascular control mechanisms show features characteristic of autoregulation which require a sensor,