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Journal of Experimental Biology, Vol 202, Issue 20 2787-2795, Copyright © 1999 by Company of Biologists
JOURNAL ARTICLES |
S Dragon, C Carey, K Martin and R Baumann
University of Regensburg, Department of Physiology, Germany, University of Colorado, Department of EPO Biology, Boulder, CO 80309, USA and Canadian Wildlife Service, Rural Route 1, Delta, British Columbia, Canada, V4K 3N2. Stefanie.dragon@vkl.
In chick embryos, developmental changes of the blood oxygen tension control hemoglobin (Hb) oxygen affinity via modulation of ATP and 2, 3BPG concentrations in red blood cells. Hypoxia, which is a normal developmental condition for late chick embryos, causes a decrease of the red cell ATP concentration (and increase of red cell oxygen affinity) as well as activation of 2,3BPG synthesis via cyclic AMP-dependent signaling. Adenosine and catecholamines have been implicated as signaling substances in these red cell responses. To assess the extent to which adenosine and catecholamines are involved in vivo in the control of red cell ATP/2,3BPG concentrations, day 13 chick embryos were treated for 24 h with adenosine A(2) and/or (&bgr;)-adrenergic receptor blockers and red cell ATP and 2,3BPG levels were determined. The data suggest that adaptive effects later in development in chick embryos induced by adenosine and catecholamines are vital. We have also tested whether avian embryos of the free-living, high-altitude, native white-tailed ptarmigan (Lagopus leucurus) alter their organic phosphate pattern in red cells in response to incubation at different altitudes. Embryos incubated at 3600-4100 m decrease their red cell ATP concentration much more rapidly than embryos of the same clutch incubated at 1600 m. From these data it can be inferred that the oxygen affinity of high altitude embryos will be adjusted to the altitude at which the eggs are incubated.
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  M. Mass, E. Simo, and S. Dragon Erythroid pyrimidine 5'-nucleotidase: cloning, developmental expression, and regulation by cAMP and in vivo hypoxia Blood, December 1, 2003; 102(12): 4198 - 4205. [Abstract] [Full Text] [PDF]
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S. Dragon and R. Baumann Erythroid carbonic anhydrase and hsp70 expression in chick embryonic development: role of cAMP and hypoxia Am J Physiol Regulatory Integrative Comp Physiol, March 1, 2001; 280(3): R870 - R878. [Abstract] [Full Text] [PDF]
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S. Dragon, N. Offenhauser, and R. Baumann cAMP and in vivo hypoxia induce tob, ifr1, and fos expression in erythroid cells of the chick embryo Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2002; 282(4): R1219 - R1226. [Abstract] [Full Text] [PDF]
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