Preparation Note Store ionomycin in powder form desiccated and protected from light at 2-8 °C. Under these conditions the product is stable for 3 years. Store stock solutions in ethanol or DMSO at -20 °C, protected from light. Under these conditions the stock solutions are stable for several months. For short term use (up to 6 weeks) the stock solutions maybe stored at 2-8 °C protected from light. Biochem/physiol Actions Ca2+ ionophore that is more effective than A23187 as a mobile ion carrier for Ca2+; non-fluorescent; used to study Ca2+ transport across biological membranes; induces apoptotic degeneration of embryonic cortical neurons.