Effect of short-duration constant exercise on permeability of cockerel aorta to ¹²⁵I-albumin

¹ Departments of Medicine and Physiology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73190

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 µCi 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° 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 < 0.20); wall 3.38 ± 5.64% and 6.42 ± 4.72 (P < 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 < 0.2). U was greater in the exercise group in 9 out of 12 matched pairs (P < 0.05). We conclude that U increases for short periods of constant exercise.

Submitted on August 10, 1984
Accepted on April 10, 1985