Coelenterazine hcp is a synthetic bioluminescent luciferin that displays an emission maximum of 445 nm.1It has been used as a calcium indicator and substrate to quantifyRenillaluciferase activity.1,2,3 1.Sabnis, R.W.Handbook of biological dyes and stains: Synthesis and industrial applications(2010) 2.Shimomura, O., Kishi, Y., and Inouye, S.The relative rate of aequorin regeneration from apoaequorin and coelenterazine analoguesBiochemistry Journal296(Pt 3)549-551(1993) 3.Pichler, A., Prior, J.L., and Piwnica-Worms, D.Imaging reversal of multidrug resistance in living mice with bioluminescence: MDR1 P-glycoprotein transports coelenterazineProc. Natl. Acad. Sci. USA.101(6)1702-1707(2004)