Ionomycin (INM)

Ionomycin is an ionophore produced by the bacterium Streptomyces conglobatus. It is used in research to raise the intracellular level of calcium (Ca2+) and as a research tool to understand Ca2+ transport across biological membranes. It is also used to stimulate the intracellular production of the following cytokines; interferon, perforin, IL-2, and IL-4 - usually in conjunction with PMA. These cytokines are important in the inflammatory response. Many receptor-linked agents that prime or activate the NADPH oxidase in polymorphonuclear neutrophils (PMNs) elicit changes in cytosolic Ca2+ concentration and activate mitogen-activated protein (MAP) kinases. Chelation of cytosolic but not extracellular Ca2+ completely inhibited ionomycin activation of p38 MAP kinase, whereas chelation of extracellular Ca2+ abrogated activation of p42/44 MAP kinase.