Restricted postexercise pulmonary diffusion capacity and central blood volume depletion

Area of Science:

• Exercise Physiology
• Cardiopulmonary Function
• Biomedical Engineering

Background:

• Pulmonary diffusion capacity for carbon monoxide (DLCO) is a key measure of lung function.
• Exercise can alter blood volume distribution and impact DLCO.
• Atrial natriuretic peptide (ANP) plays a role in fluid balance.

Purpose of the Study:

• To investigate the effects of intense rowing exercise on DLCO, blood volume distribution, and plasma ANP levels.
• To determine the relationship between changes in pulmonary blood volume and DLCO post-exercise.
• To explore the role of ANP in post-exercise cardiovascular regulation.

Main Methods:

• Measurements of DLCO, regional electrical impedance (Z0), and technetium-99m-labeled erythrocyte distribution before and after a 6-minute "all-out" row.
• Assessment of plasma ANP concentration in nine oarsmen and six control subjects.
• Comparison of responses in upright seated and supine positions.

Main Results:

• Post-exercise, DLCO decreased significantly in oarsmen (6-12%), accompanied by an increased thoracic-to-thigh electrical impedance ratio (10-14%).
• This impedance change indicated a redistribution of blood volume, with decreased thoracic and increased thigh volumes.
• Plasma ANP concentration decreased post-exercise (P < 0.05), correlating with reduced pulmonary blood volume and DLCO.
• DLCO remained stable in the control group, highlighting exercise-induced effects.

Conclusions:

• Approximately 50% of the post-exercise reduction in DLCO is attributable to a decrease in pulmonary blood volume.
• Reduced central blood volume post-exercise, evidenced by lower ANP levels, is a significant factor.
• ANP may play a role in the upregulation of blood volume following strenuous exercise in athletes.