Cellular effects of an aqueous solution of Losartan® on the survival of Escherichia coli AB1157 in the presence and absence of SnCl2, and on the physiological property (osmotic fragility) of the erytrocyte

Abstract

The angiotensin receptors type 1 (AT1) have affinity by Losartan®, low affinity to non-peptides antagonists and similar effect as Angiotensin-convert-enzyme inhibitors. It have been reported that natural and synthetic products might reduce the genotoxic and cytotoxic effects related to stannous chloride (SnCl2). SnCl2 is used in nuclear medicine as a reducing agent to obtain technetium-99 m-radiopharmaceuticals. The aim of this work was to evaluate the cellular effects produced by a solution of Losartan® (25 mg/ml) on the survival of Escherichia coli AB1157 in the presence and absence of SnCl2, and on the osmotic fragility of erythrocytes of the blood of Wistar rats. Briefly, blood sample was withdrawn by Wistar rats with heparinized syringe and incubated with Losartan® solution. Saline (NaCL 0.9%) was used as a control. The samples were gently mixed with hypotonic solutions of NaCl. After that it was centrifuged and the supernadant isolated for optical determination of the hemoglobin present. E. coli AB1157 cultures (exponential growth phase) were collected by centrifugation, washed and resuspended in 0.9%NaCl. Samples were incubated in water bath shaker with: (a) SnCl2 (25 μg/ml), (b) Losartan® (25 mg/ml) and (c) SnCl2 (25 μg/ml) + Losartan® (25 mg/ml). Incubation with 0.9% NaCl was also carried out (control). At 60 min intervals, aliquots were withdrawn, diluted, spread onto Petri dishes with solid LB medium and incubated overnight. The colonies formed were counted and the survival fractions calculated. Statistical analysis was performed. The results showed that there was a significantly increase (P < 0.05) in the osmotic fragility of the blood cells treated with Losartan®. Moreover, Losartan® was also able to protect the E. coli cultures against the lesive action of SnCl2. Although, in erythrocyte the osmotic fragility was increased by the presence of Losartan® that could 1) alter the physical properties of this cell, or 2) had a direct or indirect effect on the intracellular sodium concentration or 3) had acted on the cardiovascular system. It suggested that the Losartan® did interfere strongly with cellular metabolism and did alter the survival fractions of E. coli AB1157.