IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Effects of α-hemolysin on cell volume and intracellular sodium and potassium of human erythrocytes
Autor/es:
CANÉ, LUCÍA; ALVAREZ, CORA LILIA; HERLAX, VANESA; ISABELLE MOURO-CHANTELOUP; LEFEVRE SOPHIE DENISE; ALLEVA, KARINA; LAURI, NATALIA; LEAL DENIS MARÍA FLORENCIA; OSTUNI MARIANO ANIBAL; SCHWARZBAUM, PABLO JULIO
Lugar:
Rosario, Santa Fe
Reunión:
Congreso; Reunión Anual de la Sociedad Argentina de Fisiología; 2019
Institución organizadora:
SAFIS
Resumen:
The hemolytic toxin α-hemolysin (HlyA) is a virulence factor produced by several strains of Escherichia coli. It is involved in urinary tract infections, peritonitis, meningitis and septicemia. HlyA causes lysis of mammalian cells, including human erythrocytes (RBCs). In this work, we studied the extent to which changes in cell volume kinetics and the concentration of intracellular diffusible ions affect cell volume regulation of RBCs exposed to HlyA. RBCs from healthy donors and from aquaporin 1 KOs (AQP1KO) individuals were used.Cells at hematocrit 10% were treated with 0.1 ng/μl HlyA or vehicle at 37 °C for 1, 5 and 10 min. Cell volume was measured using the coulter counter principle, while cell volume changes at short periods of time were assessed by light scattering using a stopped flow rapid mixing equipment. For stopped flow experiments exponential curves were fitted to data and best fit exponential coefficients (k) were used to compare treatments. Intracellular concentrations of sodium and potassium were evaluated by flame photometry of lysed RBCs. HlyA induced changes in volume and shape of RBCs, which shrunk during the first min followed by continuous swelling, reaching 10% over control values after 10 min. Under a similar treatment, volume changes correlated with a 5-8 fold increase of intracellular Na+ and 5-7 fold decrease of intracellular K+ concentrations.In wild type RBCs, cell volume kinetics was affected by toxin treatment. Values of k were 8.5 ± 0.5 seg-1 for untreated cells vs 6.5 ± 0.4, 4.1 ±0.4 and 3.4 ±0.3 seg-1 for cells treated with the toxin for 1, 5 and 10 min, respectively. In the absence of toxin, k values were 5 fold lower for AQP1KO cells, as compared to wild type cells. Nevertheless, the relative decrease of k values upon HlyA exposure was similar for both types of cells.HlyA dependent decrease of volume, followed by swelling, correlated with acute and simultaneous Na+ uptake and K+ efflux. Values of the kinetic constant k decrease with time of exposure to the toxin, irrespective of the presence of aquaporin 1 in the cells.