Catheterization of pulmonary artery in rats with an ultraminiature catheter pressure transducer

Utilizing new materials and miniaturization techniques, an ultraminiature catheter pressure transducer for catheterization of the pulmonary artery (PA) has been developed and applied in intact, spontaneously breathing, anesthetized rats. The catheter arrangement consists of three components: 1) an SPR-671 ultraminiature pressure transducer (measuring catheter), 2) a plastic introducer (sheath) that is slipped over the measuring catheter, and 3) an external wire mounted on the outside of the introducer for bending its tip. The measuring catheter is first inserted through the right jugular vein into the right ventricle. The introducer is then slipped over it. The tip of the introducer is bent so that there is an angle of approximately 90 degrees or less to the shaft. The measuring catheter is advanced across the pulmonary valve into the PA. Measurements of pulmonary arterial pressure were made in five male Long Evans (364 +/- 7 g body wt) and five female Sprague-Dawley (244 +/- 7 g body wt) rats under control conditions. The effects of infusion of norepinephrine (0.1 mg.kg(-1).h(-1) iv for 20-min duration) were tested in Long Evans rats. Pulmonary arterial systolic pressure measurements were 34.0 +/- 0.8 and 29.5 +/- 0.4 mmHg, and diastolic pressure values were 23.6 +/- 0.8 and 18.1 +/- 0.6 mmHg in male Long Evans and female Sprague-Dawley rats, respectively. Norepinephrine induced an increase in pulmonary arterial systolic (40.8 +/- 0.1 mmHg) and diastolic (28.6 +/- 0.4 mmHg) pressures and an elevation in pulmonary vascular resistance from a control value of 0.093 +/- 0.003 to 0.103 +/- 0.004 mmHg.kg.min.ml(-1).