In vivo oxygen transport in the normal rabbit femoral arterial wall

Abstract

In vivo measurements of tissue oxygen tension were made at 10-μm intervals through functioning in situ rabbit femoral arterial walls, using inhalation anesthesia and recessed microcathodes with ~4-μm external diameters. External environment was controlled with a superfusion well at 30 torr P(O2), 35 torr P(CO2). Blood pressure, gas tension levels, and blood pH were held within the normal range. Radial P(O2) measurements closely fit a mathematical model for unidimensional diffusion into a thick-walled artery with uniform oxygen consumption, and the distances traversed fit measured dimensions of quick-frozen in vivo sections. Using standard values for diffusion and solubility coefficients, mean calculated medial oxygen consumption was 99 nl0/ml-s. Mural oxygen consumption appeared to be related linearly to mean tangential wall stress. Differences in experimental design and technique were compared with previous in vivo and in vitro measurements of wall oxygenation, and largely account for the varying results obtained. Control environment external to the artery, and maintenance of normally flowing blood in the lumen in vivo appeared critical to an understanding of mural oxygenation in life. If the conditions of this experiment prevailed in arteries with thicker avascular layers, P(O2) could have been 20 torr at ~156 μm and 10 torr at 168 μm from blood (average values).