Systemic oxygen transport and erythropoiesis in the mouse

Abstract

Removal of 15% of blood volume in the mouse increases erythropoiesis by a factor of 2.2 when measured 12 h after bleeding. Exposure of normal mice to 40% reduced barometric pressure for the same period of time increases erythropoiesis only by a factor of 1.6. The response to hypoxia takes place in the presence of a 40% reduction of oxygen consumption and tissue-venous PO2, changes which are concomitant with a 5-fold increase in plasma erythropoietin activity. The larger response in anemic animals on the other hand occurs without any detectable change in these parameters. These results cast serious doubts about the interpretation of the quantitative homeostatic control of erythropoiesis based solely on the action of erythropoietin.

Temporal changes of plasma erythropoietin level in hypobaric hypoxic mice and the influence of an altered blood oxygen affinity.

“…Quite inconsistent findings have been reported in previous literature. The peak value of plasma Epo was observed at as early as 8 h of exposure to 4,200 m simulated altitude (SCARO et al, 1984), and after 2 days' exposure to either 5,440 m (DUNK et al, 1976) or 9,330 m (DUNK et al, 1980 simulated altitude. Others reported the peak after 16 h at 5,440 m (FINNE, 1965) and at earlier time under more severe hypoxia (ABBRECHT and LITTELL, 1972).…”

“…But, the quantitative relationship between hypoxia and Epo production remains to be examined. For example, although a rapid increase in plasma Epo is usually observed after hypoxic exposure (FINNS, 1965;ABBRECHT and LITTELL, 1972;RUSSELL and KEIGHLEY, 1972;SCHOOLEY and MAHLMANN, 1975;DUNN et al, 1976DUNN et al, , 1980SCARO et al, 1984), the peak times range widely from 8 h (SCARO et al, 1984) to 2 days (DUNK et al, 1976(DUNK et al, , 1980 in mice. These variations have been ascribed to the differences of sex (RUSSELL and KEIGHLEY, 1972), strain (RUSSELL and KEIGHLEY, 1972), as well as Epo assay method used.…”