Eight dogs were made hypoxemic by surgical construction of a right-to-left cardiac shunt; and they were given
sodium ortho-iodobenzoate (
OISB) before and for 3 months after operation. The P(50) at 50% saturation) rose from 27.2 +/- 0.7 to 31.2 +/- 0.6 mm Hg (p less than 0.001) during OLSB treatment before operation and increased further to 32.2 +/- 0.8 mm Hg 3 months after creation of
hypoxemia. The P(50) remained elevated for an additional 3 months after
OISB was stopped. Administration of
OISB before operation did not alter the red blood cell 2,3-diphosphoglycreate concentration.
Hypoxemia caused an increase of this metabolite from 0.91 +/- 0.21 to 1.50 +/- 0.28 moles/moles of
hemoglobin (p less than 0.05); the rise was not as great as that observed in hypoxemic dogs without
OISB treatment. In spite of significant
hypoxemia, hematocrit rose only slightly during the period of
OISB infusion.
OISB increased P50 and prevented the compensatory
polycythemia regularly seen when dogs are made hypoxemic. Altering
oxygen transport in this fashion may increase tissue
oxygen delivery in patients with conditions which result in tissue
hypoxia.