Oxygen Autoregulation in Skeletal Muscle
Almost 100 years ago SEVERINI  discovered that local changes in PO2 altered the caliber of small blood vessels. To this day, however, we still do not understand this phenomenon [DULING, 1972] now referred to as oxygen autoregulation. Two major questions remain to be answered. What exactly are the local circulatory changes? And how are these changes mediated? Oxygen autoregulation can be defined as the active, rapid adaptation of the tissue oxygen supply system to changes in the availability or utilization of oxygen. It occurs in all tissues, to a greater or lesser extent, and involves both systemic and local adjustments. In order to separate oxygen autoregulation from other phenomena, such as pressure autoregulation, oxygen must be the only variable. The objective here was to study the intensity and dynamics of the response within an intact skeletal muscle (canine gracilis) to changes in oxygen availability, with all other systemic parameters constant, and, from the observed dynamics, to model the local circulatory changes in oxygen autoregulation. An input-output method identical to the one already employed to study tissue oxygen transport [GOLDSTICK et al., 1969; WAGNER, 1971; GOLDSTICK et al., 1973] was used here to study oxygen autoregulation. Its great advantage was that it left the muscle as intact as possible. To keep all other systemic parameters (such as blood pressures, gracilis muscle blood flow rate, and muscle oxygen consumption rate) constant, all tests were conducted with the animal euoxic, i.e., at or above normal PO2.
KeywordsMuscle Blood Flow Gracilis Muscle Oxygen Transport System Internal Rearrangement Pressure Autoregulation
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