Effect of econazole on membrane calcium transport in rat thymocytes

Econazole, one of azole antifungals, is proven to exhibit an inhibitory action on Mycobaterium tuberculosis and its multidrug-resistant strains under in vitro and ex vivo conditions. However, econazole has been used as a pharmacological tool for inhibiting capacitative Ca2+ influx and exerts multiple effects on cellular Ca2+ circumstance. Therefore, to suggest the toxic effect of econazole at therapeutic concentrations, we have tested on the effect on membrane Ca2+ transport in rat thymocytes by using a flow cytometer with Fluo-3, an indicator of intracellular Ca2+. Econazole at concentrations of 1-3 μM increased membrane Ca2+ permeability and inhibited capacitative Ca2+ influx without affecting passive Ca2+ influx, Ca2+ release from intracellular Ca2+ store sites, and membrane Ca2+ pump. Econazole at 0.3 μM, a therapeutic concentration against tuberculosis caused by multidrug-resistant and latent M. tuberculosis, did not affect membrane Ca2+ transport. It may be suggested that econazole at therapeutic concentrations exerts no side effect related to Ca2+