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Beta-Adrenergic Blockade Does not Prevent Polycythemia or Decrease in Plasma Volume in Men at 4300 m AltitudeWhen humans ascend to high altitude (ALT) their plasma volume (PV) and total blood volume (BV) decrease during the first few days. With continued residence over several weeks, the hypoxia-induced stimulation of erythropoietin increases red cell production which tends to restore BV. Because hypoxia also activates the beta-adrenergic system, which stimulates red blood cell production, we investigated the effect of adrenergic beta-receptor inhibition with propranolol on fluid volumes and the polycythemic response in 11 healthy unacclimatized men (21-33 years old exposed to an ALT of 4300 m (barometric pressure 460 Torr) for 3 weeks on Pikes Peak, Colorado. PV was determined by the Evans blue dye method (PV(sub EB)), BV by the carbon monoxide method (BV(sub CO)), red cell volume (RCV)was calculated from hematocrit (Hct) and BV(sub CO), and serum erythropoietin concentration ([EPO]) and reticulocyte count, were also determined. All determinations were made at sea level and after 9-11 (ALT-10) and 9-20 (ALT-20) days at ALT. At sea level and ALT, six men received propranolol (pro, 240 mg/day), and five received a placebo (pla). Effective beta-blockade did not modify the mean (SE) maximal values of [EPO] [pla: 24.9 (3.5) vs pro: 24.5 (1.5) mU/ml] or reticulocyte count [pla: 2.7 (0.7) vs pro: 2.2 (0.5)%]; nor changes in PV(sub EB)[pla: -15.8 (3.8) vs pro: -19.9 (2.8)%], RCV(sub CO) [pla: +7.0 (6.7) vs pro: +10.1 (6.1)%], or BV(sub CO) [pla: -7.3 (2.3) vs pro: -7.1 (3.9)%]. In the absence of weight loss, a redistribution of body water with no net loss is implied. Hence, activation of the beta-adrenergic system did not appear to affect the hypovolemic or polycythemic responses that occurred during 3 weeks at 4300 m ALT in these subjects.
Document ID
20000069644
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Grover, R. F.
(Colorado Univ. Denver, CO United States)
Selland, M. A.
(Colorado Univ. Denver, CO United States)
McCullough, R. G.
(Colorado Univ. Denver, CO United States)
Dahms, T. E.
(Saint Louis Univ. School of Medicine Saint Louis, MO United States)
Wolfel, E. E.
(Colorado Univ. Denver, CO United States)
Butterfield, G. E.
(Palo Alto Veterans Administration Health Care System Palo Alto, CA United States)
Reeves, J. T.
(Colorado Univ. Denver, CO United States)
Greenleaf, J. E.
(NASA Ames Research Center Moffett Field, CA United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1998
Publication Information
Publication: European Journal of Applied Physiology
Publisher: Springer-Verlag
Volume: 77
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: NIH-HL-14984
CONTRACT_GRANT: DAMD17-91-C-1112
PROJECT: RTOP 199-18-12-07
CONTRACT_GRANT: NIH-HL-46481
Distribution Limits
Public
Copyright
Other

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