Catheterization of the pulmonary artery in the closed-chest rat

A simple technique has been devised to catheterize the pulmonary artery in rats for measurement of pulmonary artery pressure. A no. 3 1/2 French umbilical vessel catheter (Argyle), angled to 90 degrees over the distal 1 cm, was introduced into the right external jugular vein of the anesthetized (50 mg/kg pentobarbital sodium, ip) rat (male Wistar, 250–350 g). With the angle directed anteriorly, the catheter was inserted 2.5 cm proximally, which placed the catheter in the right atrium. The catheter was rotated 90 degrees counterclockwise and inserted 1.0 cm further, which placed the catheter in the right ventricle. Advancement of the catheter an additional 1.5 cm allowed placement in the pulmonary artery. Placement at each stage was confirmed by the respective pressure contours. This technique is easily and rapidly performed and has many potential applications in measuring parameters of the pulmonary circulation in a variety of small laboratory animals.