Tracheobronchial perfusion during exercise in ponies.

This research investigated the blood flow to the trachea and bronchi in ponies during exercise, and found that bronchial blood flow increases significantly during the 10th minute of exertion possibly to help dissipate body heat.

Objective and Methodology

• The researchers sought to study blood flow to the trachea and bronchi (up to the 7th generation of branching) in seven healthy adult ponies at rest and during exercise.
• The exercise was carried out on a treadmill at a speed setting of 25 km/h. The conditions of the air around had a temperature ranging from 19 to 20 degrees Celsius and humidity from 35 to 45%
• To measure blood flow, the team used radionuclide-labeled microspheres (tiny spherical particles), which were injected into the left ventricle of the heart through a catheter advanced from the left carotid artery. A reference sample was obtained from the aorta.
• They ensured that the microspheres mixed adequately with the blood by checking for similar perfusion values for the left and right kidneys.

Findings

• The ponies’ heart rate and mean aortic pressure increased during exercise.
• At rest, tracheal blood flow of the ponies was one third of the bronchial blood flow. There were no significant changes in tracheal perfusion during the 3rd or 10th minute of exercise.
• Bronchial blood flow did not change at the 3rd minute of exercise. However, during the 10th minute of exercise, a significant increase to 202.8 +/- 30.3 ml.min-1 x 100 g-1 was observed.
• This rise in bronchial blood flow may be attributed to the body’s need to dissipate heat, as the renal blood flow decreased during this stage of exertion.

Conclusion

• This study constitutes a noteworthy investigation into the tracheobronchial circulation during exercise in ponies. The results incite a possible theory that bronchial blood flow escalates during periods of sustained exercise as a mechanism to help cool the body’s temperature.