Journal of Applied Physiology, Vol 58, Issue 4 1257-1262, Copyright © 1985 by American Physiological Society
Effect of hematocrit reduction on hormonal and metabolic responses to exercise
D. H. Wasserman, H. Lavina, A. Lickley and M. Vranic
We wished to determine the effect of a 25% hematocrit reduction on
glucoregulatory hormone release and glucose fluxes during exercise. In five
anemic dogs, plasma glucose fell by 21 mg/dl and in five controls by 7
mg/dl by the end of the 90-min exercise period. After 50 min of exercise,
hepatic glucose production (Ra) and glucose metabolic clearance rate (MCR)
began to rise disproportionately in anemics compared with controls. By the
end of exercise, the increase in Ra was almost threefold higher (delta 15.1
+/- 3.4 vs. delta 5.2 +/- 1.3 mg X kg-1 X min-1) and MCR nearly fourfold
(delta 24.6 +/- 8.8 vs. delta 6.5 +/- 1.3 ml X kg-1 X min-1). Exercise with
anemia, in relation to controls resulted in elevated levels of glucagon
[immunoreactive glucagon (IRG) delta 1,283 +/- 507 vs delta 514 +/- 99
pg/ml], norepinephrine (delta 1,592 +/- 280 vs. delta 590 +/- 155 pg/ml),
epinephrine (delta 2,293 +/- 994 vs. delta 385 +/- 186 pg/ml), cortisol
(delta 6.7 +/- 2.2 vs. delta 2.1 +/- 1.0 micrograms/dl) and lactate (delta
12.1 +/- 2.2 vs. delta 4.2 +/- 1.8 mg/dl) after 90 min. Immunoreactive
insulin and free fatty acids were similar in both groups. In conclusion,
exercise with a 25% hematocrit reduction results in 1) elevated lactate,
norepinephrine, epinephrine, cortisol, and IRG levels, 2) an increased Ra
which is likely related to the increased counterregulatory response, and 3)
we speculate that a near fourfold increase in MCR is related to metabolic
changes due to hypoxia in working muscle.(ABSTRACT TRUNCATED AT 250 WORDS)
