Effect of Increased Blood Oxygen Affinity on Work Performance of Rats

Abstract

A B S T R A C T Influence of altered blood oxygen affinity on maximal performance ability was evaluated in trained rats exercising to exhaustion in a graded treadmill test. Modification of blood oxygen affinity was achieved both by 2,3-diphosphoglycerate depletion, accomplished by exposure of animals to C02 and by exchange transfusion with blood exposed to bisulfite or stored in acid citrate dextrose, and by carbamylation of hemoglobin, produced by exchange transfusion of blood incubated with potassium cyanate. A decrease in oxygen tension at half-saturation of hemoglobin (P5o) from 36 to 23 mm Hg produced a decrease in resting central venous oxygen pressure of about 12 mm Hg. During exercise it caused an average decrease in work performance of about 10%, which was equivalent to that performance decrement caused by a decrease in hemoglobin concentration of approximately 10%. When superimposed on anemia, this change in blood oxygen affinity again caused a similar decrease in performance over and above that due to anemia alone. A marked rightward shift of the in vivo oxygen dissociation curve during severe exercise may have compensated for the reduced in vitro P5o.

Tissue oxygenation and muscular substrate turnover in two subjects with high hemoglobin oxygen affinity.

“…Some authors claim that an increased Hb oxygen affinity has a detrimental effect on tissue oxygenation (5-7), whereas others have found that an increased Hb oxygen affinity is of no disadvantage or only a slight disadvantage in this respect (8)(9)(10)(11)(12)(13). One explanation for the varying opinions may be that different organs have been studied.…”

“…The experimental evidence for this, however, is conflicting. Some authors have found a detrimental effect of a leftshifted ODC (5-7), while others have found it to be of either no or only a slight disadvantage (8)(9)(10)(11)(12). In a recent study (13), we measured tissue oxygen pressure in rats with increased hemoglobin oxygen affinity without finding any untoward effects.…”

Characteristics of blood gas in response to iron treatment and exercise in iron-deficient and anemic subjects.

“…The It has been shown that the greater the severity of anemia in humans and rats, the greater the decrement in work capacity (1)(2)(3)(4)(5)(6)(7)(8). Decreased O2 carrying capacity of blood (7) and decreased O2 utilizing capacity of tissues (1, 3, 9-11, 26, 27) decreased maximal capacity of O2 consumption (7).…”

Effects of Shifts in Hemoglobin-Oxygen Affinity During Hypoxia

“…Valeri and Collins [11], for example, observed no effect on oxygen consumption or cardiac output in eight patients who received up to 2,500 ml of low 2,3-diphosphoglycerate donor blood. Woodson et al [12] found that the work per formance of rats was relatively unaffected by exchange transfusion which resulted in a marked increase in hemoglobin-oxygen affinity. Recently, Riggs et al [9] have reported no change in oxygen consumption or cardiac output in Rhesus monkeys in which oxygen affinity was increased by similar means.…”