AJP - Cell Physiology, Vol 256, Issue 4 C925-C929, Copyright © 1989 by American Physiological Society
Erythropoietin production in exhypoxic polycythemic mice
I. Seferynska, J. Brookins, J. C. Rice and J. W. Fisher
Department of Pharmacology, Tulane University School of Medicine, New Orleans, Louisiana 70112.
Our present study was undertaken to determine the serum erythropoietin
concentration (radioimmunoassay), hematocrit, red cell mass, and body
weight of mice exposed to hypoxia in a hypobaric chamber (0.42 atm, 22
h/day) for 14 days and during the 10 posthypoxic days at ambient pressure
to clarify the correlation of the red cell mass and erythropoietin
production during hypoxia. The mean serum erythropoietin titer was 326.23
+/- 77.04 mU/ml after 2 days, reached the highest level after 3 days (452.2
+/- 114.5 mU/ml), then gradually declined to a level of 36.5 +/- 11.4 mU/ml
after 14 days of hypoxia, and was undetectable during the 10-day
posthypoxic period. The hematocrit values were significantly increased from
41.09 +/- 0.50% at day 0 to 51.65 +/- 1.08% after 3 days and to 72.20 +/-
1.53% after 14 days of hypoxia. The red cell mass (calculated from initial
body weight) increased from 3.24 +/- 0.1 ml/100 g at day 0 to 7.32 +/- 0.46
ml/100 g after 14 days of hypoxia and declined to 6.66 +/- 0.53 ml/100 g at
the end of the 10-day posthypoxic period. The mice lost weight while they
were in the hypobaric chamber and showed a significant increase in body
weight during the 10-day posthypoxic period. These studies support the
concept that chronic intermittent hypoxia causes an early increase,
followed by a rapid decline, in erythropoietin production, which is
correlated with the gradual increase in red cell mass.
