Of the three intracellular Ca2+ signalling molecules (InsP(3), cADPR and NAADP) sea urchin egg homogenate has been used in the identification and characterisation of two, cADPR and NAADP. Homogenate is prepared in a Na+/Cl- substitute of N-Methyl glucamine (NMG)/gluconate. To determine how media composition affects Ca2+ release we replaced NMG with various sugars or glycine and found a dramatic improvement in InsP(3) mediated Ca2+ release. Conversely the response to cADPR was diminished, whilst NAADP was unaffected. Therefore modifying media composition may be an important consideration in using homogenate to study Ca2+ release for future studies. (c) 2007 Elsevier Inc. All rights reserved.