Intracellular pH in unanesthetized dogs during panting

Area of Science:

• Physiology
• Environmental Medicine
• Animal Science

Background:

• Heat stress significantly impacts physiological parameters in animals.
• Understanding cellular responses to heat is crucial for animal welfare and performance.
• Intracellular pH regulation is vital for cellular function.

Purpose of the Study:

• To investigate the effects of mild and severe heat stress on intracellular pH, blood gases, and plasma enzymes in dogs.
• To evaluate the efficacy of CO2 exposure in mitigating heat stress responses.

Main Methods:

• Unanesthetized dogs were exposed to controlled heat conditions (30°C/50% RH and 40°C/50% RH).
• Measurements included intracellular pH, arterial blood gases, and plasma enzyme levels.
• Experiments included exposure to 4% CO2 in the climatic chamber during heat stress.

Main Results:

• Mild heat stress showed no significant changes.
• Severe heat stress induced respiratory alkalosis and increased intracellular pH from 7.03 to 7.29.
• Plasma enzymes increased by over 300% during severe heat stress.
• CO2 exposure inhibited respiratory alkalosis and enzyme increase, with more efficient heat dissipation and lower body temperature (39.8°C).

Conclusions:

• Intracellular buffering capacity is insufficient to prevent significant intracellular pH shifts during panting under heat stress.
• CO2 administration can ameliorate detrimental physiological responses to heat stress in dogs.
• Ventilatory heat dissipation is a critical factor in thermoregulation.