In vitro activity: Ramipril is an angiotensin-converting enzyme (ACE) inhibitor with IC50 of 5 nM. Ramipril enhances the activity of ACE-associated CK2 and the phosphorylation of ACE Ser1270 in cultured endothelial cells, but is unable to activate JNK or stimulate the nuclear accumulation of c-Jun in endothelial cells expressing a S1270A ACE mutant or in ACE-deficient cells. Prolonged Ramipril treatment increases ACE expression in primary cultures of human endothelial cells and in vivo (mouse lung), which can be prevented by pretreatment with the JNK inhibitor SP600125. Ramipril displays little enhanced effect on the rate of in vitro endothelial apoptosis induced by the serum deprivation method.

Cell Assay: The HUVECs are pretreated with the active metabolites of Ramipril for 24 hours. A serum deprivation method is used to induce apoptosis in the presence of Ramipril for an additional 24 hours. The rate of apoptosis is then determined using flow cytometry with two makers annexinV fluorescein isothiocyanate (FITC+) and propidium iodide (PI).