HUMAN CARDIAC FIBROBLASTS EXPRESS AN ANGIOTENSIN RECEPTOR WITH UNUSUAL, BINDING CHARACTERISTICS WHICH IS COUPLED TO CELLULAR PROLIFERATION

To assess the cellular localization of angiotensin receptors in human heart, we isolated human cardiac fibroblasts from explanted end-stage failing human hearts. As judged by an immunofluorescence assay, the is olated cells consisted to 96% of fibroblasts. Using receptor binding s tudies, we could identify a single angiotensin binding site on these c ells, with a Kd of 0.6nM and a Bmax of 1.5 fmol/mg protein. Inhibiting concentrations 50 for Ang II and Ang I/II (1-7) were 40nM and 10nM, r espectively. Stimulation with Ang II (100nM) and Aug I/II (1-7) (100nM ) led to cellular proliferation which could not be inhibited by Losart an or PD 123319. These results suggest that human cardiac fibroblasts express an as yet unknown angiotensin receptor-subtype. (C) 1994 Acade mic Press, Inc.