A novel right-heart catheterization technique for in vivo measurement of vascular responses in lungs of intact mice

The present study employed a new right-heart catheterization technique to m easure pulmonary arterial pressure, pulmonary arterial wedge pressure, and pulmonary vascular resistance in anesthetized intact-chest, spontaneously b reathing mice. Under fluoroscopic guidance, a specially designed catheter w as inserted via the right jugular vein and advanced to the main pulmonary a rtery. Cardiac output was determined by the thermodilution technique, and m easured parameters were stable for periods of less than or equal to 3 h. Pr essure-flow curves in vivo were curvilinear, with mean pulmonary arterial p ressure increasing more rapidly at low pulmonary blood flows of 5-10 ml/min and less rapidly at higher blood flow rates. The pressure-flow relationshi p was shifted to the left by the nitric oxide synthase inhibitor nitro-L-ar ginine methyl ester (L-NAME) at higher blood flow levels, whereas the cyclo oxygenase inhibitor sodium meclofenamate was without effect. The increase i n pulmonary arterial pressure in response to acute hypoxia (fractional insp ired O-2 10%) was augmented by L-NAME but unaltered by sodium meclofenamate . The present results demonstrate that the right-heart catheterization tech nique can be used to measure pulmonary vascular pressures and responses in the mouse. This is, to our knowledge, the first report of a right-heart cat heterization technique to measure pulmonary vascular pressures and response s in the intact-chest, spontaneously breathing mouse and should prove usefu l for the investigation of pulmonary vascular responses in transgenic mice.