A method to maintain normal respiratory and metabolic state in artificially respired rats

Analysis of arterial blood gases (ABG) in awake, paralyzed, locally anesthetized, and artificially respired rats revealed the development with time of severe hypoxemia associated with metabolic acidosis despite adequate ventilation as assessed by normal Paco₂. These respiratory and metabolic disturbances may underlie the progressive deterioration experienced with this preparation frequently used in neuropharmacological experiments. We report here that the intravascular infusion of bicarbonated artificial plasma, associated with continuous positive pressure ventilation, prevents the deterioration of the respiratory and metabolic state in this preparation, which can be maintained within the range of that of the freely moving animal. This stabilized preparation may thus be highly suitable for neuropharmacological experiments extending for several hours.