Cardiotoxicity induced by excretion product of Shigella dysenteriae (PEShi) and protection of magnesium chloride (MgCl2): An assessment with fluorescent probes

The study aimed to assess changes in cell structure and fluorescent labeling issued by subcellular organelles, lysosomes and mitochondria, in cardiac myoblasts treated with the excretion product of Shigella dysenteria (PEShi) and in combination with Magnesium Chloride (MgCl2). Cardiac myoblasts derived from chicken embryo heart tissue culture in Hanging-Drop, were randomly selected and divided into four groups: a) Control (Tyrodes solution, 0.1 mL, 1 hour), b) PEShi (0.1 mL, 30 min), c) MgCl2 (0.1 mL, 123.65 mM, 30 min) and d) MgCl2 (30 min) + PEShi (30 min), all incubated at 37° C. After treatment, the respective samples were fixed in 10% buffered formalin for 1 min and stained with HE for 1 min. Morphological changes were evaluated by morphometry through measurements the nuclear, cytoplasmic and area cell. Cell death was estimated as a percentage of cells with rounded morphology. Another group of samples were incubated with Acridine Orange (5 mg / mL, 0.1 mL, 10-3M, 2 min) and DiOC1 (3) (5 mg / mL, 0.1 mL, 10-3M, 1 min). Elapsed respective treatments the samples were observed under fluorescence microscope with excitation at 460-490 nm and 510-550 nm. Cardiac myoblasts treated with PEShi, compared with control, with treated only with MgCl 2 and the combination showed a reduction of cell area by an average of 67.56% with 92.21% mortality. PEShi treated myoblasts showed a fluorescence pattern relocation issued by the lysosomes and mitochondria. This change was reduced in the group treated with the combination MgCl2 + PEShi. The results demonstrate the cardiotoxic action induced by PEShi, probably driven by the action of Shiga toxin (Stx), which would target subcellular organelles such as lysosomes and mitochondria. Moreover, it was revealed the cardioprotective action of MgCl2.