Human erythropoietin response to hypocapnic hypoxia, normocapnic hypoxia, and hypocapnic normoxia

TY - JOUR

T1 - Human erythropoietin response to hypocapnic hypoxia, normocapnic hypoxia, and hypocapnic normoxia

AU - Klausen, T

AU - Christensen, H

AU - Hansen, J M

AU - Nielsen, O J

AU - Fogh-Andersen, N

AU - Olsen, Niels Vidiendal

PY - 1996

Y1 - 1996

N2 - This study investigated the human erythropoietin (EPO) response to short-term hypocapnic hypoxia, its relationship to a normoxic or hypoxic increase of the haemoglobin oxygen affinity, and its suppression by the addition of CO2 to the hypoxic gas. On separate days, eight healthy male subjects were exposed to 2 h each of hypocapnic hypoxia, normocapnic hypoxia, hypocapnic normoxia, and normal breathing of room air (control experiment). During the control experiment, serum-EPO showed significant variations (ANOVA P = 0.047) with a 15% increase in mean values. The serum-EPO measured in the other experiments were corrected for these spontaneous variations in each individual. At 2 h after ending hypocapnic hypoxia (10% O2 in nitrogen), mean serum-EPO increased by 28% [baseline 8.00 (SEM 0.84) U.l-1, post-hypoxia 10.24 (SEM 0.95) U.l-1, P = 0.005]. Normocapnic hypoxia was produced by the addition of CO2 (10% Co2 with 10% O2) to the hypoxic gas mixture. This elicited an increased ventilation, unaltered arterial pH and haemoglobin oxygen affinity, a lower degree of hypoxia than during hypocapnic hypoxia, and no significant changes in serum-EPO (ANOVA P > 0.05). Hypocapnic normoxia, produced by hyperventilation of room air, elicited a normoxic increase in the haemoglobin oxygen affinity without changing serum-EPO. Among the measured blood gas and acid-base parameters, only the partial pressures of oxygen in arterial blood during hypocapnic hypoxia were related to the peak values of serum-EPO (r = -0.81, P = 0.01). The present human EPO responses to hypoxia were lower than those which have previously been reported in rodents and humans. In contrast with the earlier rodent studies, it was found that human EPO production could not be triggered by short-term increases in pH and haemoglobin oxygen affinity per se, and the human EPO response to hypoxia could be suppressed by concomitant normocapnia without acidosis.

AB - This study investigated the human erythropoietin (EPO) response to short-term hypocapnic hypoxia, its relationship to a normoxic or hypoxic increase of the haemoglobin oxygen affinity, and its suppression by the addition of CO2 to the hypoxic gas. On separate days, eight healthy male subjects were exposed to 2 h each of hypocapnic hypoxia, normocapnic hypoxia, hypocapnic normoxia, and normal breathing of room air (control experiment). During the control experiment, serum-EPO showed significant variations (ANOVA P = 0.047) with a 15% increase in mean values. The serum-EPO measured in the other experiments were corrected for these spontaneous variations in each individual. At 2 h after ending hypocapnic hypoxia (10% O2 in nitrogen), mean serum-EPO increased by 28% [baseline 8.00 (SEM 0.84) U.l-1, post-hypoxia 10.24 (SEM 0.95) U.l-1, P = 0.005]. Normocapnic hypoxia was produced by the addition of CO2 (10% Co2 with 10% O2) to the hypoxic gas mixture. This elicited an increased ventilation, unaltered arterial pH and haemoglobin oxygen affinity, a lower degree of hypoxia than during hypocapnic hypoxia, and no significant changes in serum-EPO (ANOVA P > 0.05). Hypocapnic normoxia, produced by hyperventilation of room air, elicited a normoxic increase in the haemoglobin oxygen affinity without changing serum-EPO. Among the measured blood gas and acid-base parameters, only the partial pressures of oxygen in arterial blood during hypocapnic hypoxia were related to the peak values of serum-EPO (r = -0.81, P = 0.01). The present human EPO responses to hypoxia were lower than those which have previously been reported in rodents and humans. In contrast with the earlier rodent studies, it was found that human EPO production could not be triggered by short-term increases in pH and haemoglobin oxygen affinity per se, and the human EPO response to hypoxia could be suppressed by concomitant normocapnia without acidosis.

KW - Adult

KW - Anoxia

KW - Carbon Dioxide

KW - Erythropoietin

KW - Hemoglobins

KW - Humans

KW - Hydrogen-Ion Concentration

KW - Hypocapnia

KW - Male

KW - Oxygen

M3 - Journal article

C2 - 8954296

SN - 0301-5548

VL - 74

SP - 475

EP - 480

JO - European Journal of Applied Physiology and Occupational Physiology

JF - European Journal of Applied Physiology and Occupational Physiology

IS - 5

ER -