Renin expression by vascular endothelial cells in culture

Cultured bovine aortic endothelial cells were examined for renin activity by biochemical, immunological, and immunohistochemical technique. When cell sonicates were incubated with renin substrate, linear generation of angiotensin I was observed (1.12 ± 0.2 ng angiotensin I/10⁶ cells per hr). The effect of pH on this activity was similar to that of bovine renal renin, and renin antibodies inhibited a large portion of the enzymatic activity. Furthermore, immunofluorescence microscopy with antirenin antisera confirmed the presence of renin within these cells. Biosynthetic radiolabeling, followed by immunoprecipitation, demonstrated de novo synthesis of a renin precursor in the endothelial cells, which was processed to a more mature protein. Thus, bovine aortic endothelial cells in culture contain and biosynthesize renin, a key component of the renin-angiotensin system. The expression of renin activity by endothelium may contribute to the local regulation of vascular tone.