Polycythemia and changes in erythropoietin concentration in rats exposed to intermittent hypoxia.
It is not clear whether blood hemoglobin concentration ([Hb]) increases with an increase in the exposure period of intermittent hypoxia (IHx) and reaches a constant level. Furthermore, it is not known whether plasma erythropoietin concentration ([EPO]) also increases with an increase in the exposure period. Using a rat model, first, we evaluated changes in [EPO] every hour after single exposure of 10% O(2) for 120 min in order to determine a peak level of [EPO]. Second, we evaluated the effect of IHx of 10% O(2), 120 min/day for 0 (control), 1, 2, 3, 4, 6 and 8 weeks on [Hb], arterial blood pressure (BP), heart rate (HR), arterial blood gases (ABGs) and [EPO]. [EPO] increased after cessation of the single hypoxic exposure, reached a peak at 1 h, and decreased gradually to the control levels within 18 h. IHx of 10% O(2), 120 min/day, produced a time-dependent increase in [Hb], and [Hb] reached a constant level after the exposure for 6 weeks. BP increased after the exposure for 4 weeks and remained elevated. There was no significant difference in HR and ABGs. [EPO] increased significantly and remained elevated at the same level for 1-3 weeks, however, the peak level of [EPO] declined markedly after [Hb] reached a constant level.
Ishii
Makoto
M
Department of Medicine, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan.
Iwamoto
Tokuzen
T
Nagai
Asuka
A
Sasao
Gen
G
Iwasaki
Masayuki
M
Kuwahira
Ichiro
I
D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D004921:Erythropoietin / Q000378:metabolism*; D006454:Hemoglobins / Q000378:metabolism; D000860:Hypoxia / Q000150:complications* / Q000503:physiopathology; D008297:Male; D011086:Polycythemia / Q000150:complications* / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley
D006454:Hemoglobins; D004921:Erythropoietin