Arterial blood gas measurements in guinea pigs and inspired CO2 concentrations for ventilatory performance challenges

Guinea pigs were fitted with a carotid cannula under anesthesia and used 2 days later for exposure to increasing CO2 concentrations to evaluate their ventilatory response (tidal volume and respiratory frequency) while blood samples were taken for measurement of O2, CO2, and pH. The same measurements were made on another group of animals while changing O2 concentrations. The ventilatory response increased with increasing CO2 concentrations up to 10% while there was little change induced by low oxygen. Decreasing O2 during challenge of animals with 10% CO2 had no effect on the ventilatory response induced by 10% CO2 alone. The ventilatory response of guinea pigs is greater than for other small laboratory animals tested under similar conditions but is not as pronounced as in humans. Challenging guinea pigs with 10% CO2 has revealed that their ventilatory response can be abnormal following pneumotoxicity induced by a variety of agents and blood gas measurements as described here may add to our understanding of such abnormal responses.