Journal of Applied Physiology, Vol 59, Issue 3 984-990, Copyright © 1985 by American Physiological Society
Effect of short-duration constant exercise on permeability of cockerel aorta to 125I-albumin
M. D. Ezekowitz, M. A. Morgan, J. L. Kelley, D. E. Parker and H. L. Stone
To determine quantitatively the effect of short duration constant exercise
on the rate of uptake (U) of intravenously injected 125I-labeled cockerel
albumin (A) by the aorta of the adult cockerel, 24 birds divided into
age-matched pairs, each pair consisting of an exercised and nonexercised
control bird, were studied. The time period of heparinization, anesthesia,
and time from injection of A (each member of each pair received about 50
microCi from the same batch) to the death of the animal (T) was identical
for each member of each pair. The exercised animal was exercised at a
constant speed of 3.2 kph at 0 degrees elevation for between 2 and 5 min on
a treadmill. U was defined as accumulated wall radioactivity (dpm)/plasma
radioactivity (dpm/ml) X endothelial surface area (cm2) X T (s). Free 125I
in the injectate amounted to 1.29 +/- 0.31% (mean +/- SD). Free 125I in the
plasma and the wall in the exercise and control animals was not
significantly different: plasma 0.84 +/- 0.34% (mean +/- SD) and 0.55 +/-
0.18 (P less than 0.20); wall 3.38 +/- 5.64% and 6.42 +/- 4.72 (P less than
0.04). Injected A remaining in the blood at between 8 and 16 min after
intravenous injection was 83 +/- 8.7% (n = 10) in the exercised and 82 +/-
10% (n = 7) in the control (P less than 0.2). U was greater in the exercise
group in 9 out of 12 matched pairs (P less than 0.05). We conclude that U
increases for short periods of constant exercise.
