Measurement of bioactive renin concentration and renin activity in the presence of exogenous renin substrate: effect of the oral direct renin inhibitor aliskiren

Renin inhibition with aliskiren has been reported to cause a greater rise in renin than other types of reninangiotensin system (RAS) blockade.Although this might be an indication of superior RAS blockade, it could also be due to an aliskiren-induced change in the conformation of prorenin (the inactive precursor of renin), allowing its detection in renin assays, and/or a change in renin/prorenin clearance.Furthermore, when considering this rise, the aliskiren/renin stoichiometry should be taken into consideration, i.e. the number of aliskiren molecules available to block renin, even when it has increased several-fold.This talk will address the pitfalls of renin measurements during renin inhibitor treatment.It will also describe a new assay to measure prorenin directly, i.e. on the basis of its prosegment rather than its active site.