FATE OF ANGIOTENSIN I AND 2 IN HUMAN PULMONARY CIRCULATION

The systemic pressure response technic was applied in 4 patients undergoing diagnostic catheterization. Injections were made alternately into the pulmonary artery and the ascending aorta and the systemic arterial pressor responses to each of these two routes of administration were compared. In 2 subjects, the pressor potency of angiotensin II given by way of the pulmonary artery was identical to that resulting from aortic injections, thus indicating the absence of pulmonary extraction of the octapeptide. In 2 other patients, angiotensin I was twice as potent by the pulmonary than by the aortic route; this could have resulted only from the marked conversion of the inactive decapeptide under the influence of pulmonary converting-enzyme activity. These data provide the clinical confirmation of previous animal observations pointing to the important role played by the lungs in the renin-angiotensin system. Application of the systemic pressure response technic has proved to be easy and safe during cardiac catheterization in man, and it can now be used to study the fate of vasoactive drugs or hormones in the pulmonary circulation. © 1969.