The effect of furosemide on calcium ion concentration in myocardial cells

The effect of furosemide and ouabain on the intracellular concentration of Ca²⁺ was studied in myocardial cell cultures using Fura-2, a fluorescent agent, as an intracellular Ca²⁺ indicator. Introduction of 200μM ouabain to the cultured cells increased the intracellular calcium concentration from an average of 236 nM up to an average of 833 nM. Introduction of 100μM furosemide, prior to the administration of ouabain, decreased the ouabain induced Ca²⁺ elevation to an average of only 473 nM. Introduction of 2.5 mM EGTA prior to the administration of ouabain abolished the ouabain induced Ca²⁺ increase.