Differences in Tissue Angiotensin II–Forming Pathways by Species and Organs In Vitro

Abstract

—Angiotensin (Ang) II plays an important role in cardiovascular homeostasis, not only in the systemic circulation but also at the tissue level, and is involved in the remodeling of the heart and vasculature under pathological conditions. Although alternative Ang II–forming pathways are known to exist in various tissues, the details of such pathways remain unclear. The aim of this study was to examine tissue Ang II–forming activities and to identify the responsible enzyme in several organs (lung, heart, and aorta) in various species (human, hamster, rat, rabbit, dog, pig, and marmoset). Among the organs examined, the lung contained the highest Ang II–forming activity. The responsible enzyme for pulmonary Ang II formation was angiotensin I-converting enzyme (ACE) in all of the species except the human lung, in which a chymaselike enzyme was dominant. In the heart, the highest total Ang II–forming activity was observed in humans, and a chymaselike enzyme was dominant in all of the species except rabb...