Long-term modulation of the exercise ventilatory response in goats

Area of Science:

• Exercise Physiology
• Respiratory Control
• Animal Models

Background:

• The ventilatory response to exercise is crucial for maintaining homeostasis.
• Mechanisms underlying exercise hyperpnea, particularly adaptive plasticity, are not fully understood.

Purpose of the Study:

• To investigate if associating exercise with increased respiratory dead space induces adaptive changes in ventilatory control.
• To determine the repeatability and reversibility of these adaptive responses.

Main Methods:

• Adult goats underwent training involving paired exercise and increased dead space (0.8 L).
• Ventilation, arterial blood gases (PaCO2), and CO2 production were measured at rest and during exercise before and after training.
• Two experimental series were conducted to assess repeatability and dynamic responses.

Main Results:

• Post-training, resting ventilation and breathing frequency increased, while tidal volume decreased, returning to baseline after one week.
• The exercise ventilatory response increased by 25-28% 1-6 hours post-training, primarily due to increased breathing frequency.
• Arterial partial pressure of CO2 (PaCO2) decreased more during exercise post-training, indicating enhanced ventilation relative to CO2 production.

Conclusions:

• Repeated association of exercise with increased dead space induces a repeatable and reversible plasticity in the control of exercise ventilation.
• This plasticity enhances the feedforward stimulus for exercise ventilation.
• These findings suggest a significant adaptive capacity within the adult respiratory control system.