A technique for unilateral instillation of agents into the rat lung

We describe a technique for unilateral instillation of agents into the right lung of rats. We intubated rats perorally with a 16-gauge flexible polyethylene catheter and through it introduced narrow-bore (less than 1 mm diam) polyethylene tubing into the trachea and beyond the carina into the right main-stem bronchus. This maneuver was facilitated by placing the animal supine with the cephalad end tilted up and the right side tilted down. We tested the effectiveness of our technique by instilling Evans blue dye into the right lung of 14 rats and spectrophotometrically quantitating the amount of dye present in homogenates from each lobe of the right and left lungs. Ninety-seven percent of the instilled dye was recovered from the right lung, and distribution of dye per gram of tissue was uniform among the four lobes. The technique described should be useful in producing severe degrees of unilateral lung injury and fibrosis in rodents without the high mortality that can be associated with bilateral lung injury.