The Roentgenographic Determination of Traeheal Mucoeiliary Transport Rate in the Rat

An in vivo method for determination of the rate of mucoeiliary transport in the rat trachea has been developed. Briefly, an aqueous suspension of radiopaque material (barium sulfate) is deposited in the trachea of a lightly anesthetized animal through a small incision in the pharynx using a small-bore stainless-steel tube coupled to a hypodermic syringe. X-ray photographs, taken over a period of several minutes at 30-second intervals through a radiopaque measuring grid, indicate the rate of movement along the traeheal length. Intratracheal intubation of solutions of silver nitrate completely inhibited movement of radiopaque traeheal material, while, normally, the transport rate was 6 to 10 mm/min, in fair agreement with the rate reported in studies using a variety of other techniques. Since there is only minimal procedural damage to the rat, the effects of injected substances as well as environmental contaminants may be expeditiously determined by this method using the same animal repeatedly.