Studies of Metabolism, Function and Mechanism of Destruction of Red Cells.
Annual progress rept. 1 Sep 74-31 Oct 75,
ROCHESTER UNIV N Y SCHOOL OF MEDICINE AND DENTISTRY
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Propranolol reduces oxygen binding by hemoglobin in intact red cells by increasing the selective permeability of the red cell membrane to potassium. The exodus of potassium and water results in an increase in hydrogen ion concentration in the cell and a reduction in hemoglobin affinity for oxygen as a result of the Bohr effect. In patients with acute myocardial infarction, whole body oxygen consumption remains constant despite a nearly three-fold variation in arterial oxygen flow rate. Although a reduction in hemoglobin oxygen affinity could explain about one third of the increased extraction of oxygen required to maintain oxygen consumption other compensating mechanisms must be important for most of the adaptation. Water soluble radiographic contrast materials produce a significant alteration in the Donnan distribution of ions across the red cell membrane. The normal negative potential of the red cell membrane can be reduced or reversed depending on the concentration of contrast material added to blood. As the inside of the cell becomes more positive with respect to the outside, proteins are, in effect, repelled into plasma producing acidemia.
- Anatomy and Physiology