Proceedings of The Physiological Society

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCA239

Poster Communications

Role of an Enterococcus faecalis strain on hypertension. Effects on urine nitric oxide and 8-isoprostane levels.

M. Martínez-Cañamero1, A. Segarra1, S. Valiente1, A. Cobo1, M. Hidalgo1, I. Prieto1

1. Health Science, University of Jaen, Jaen, Jaen, Spain.

Hypertension is considered the most serious risk factor for cardiovascular disease. Usually, it is associated with other metabolic disorders, as obesity and glucose intolerance. In addition to drug therapies, different functional foods have been used for its treatment, indicating an important role of gut microbiota in the control of blood pressure (BP) (Ettinger et al., 2014). Moreover, other components of foods have been widely related to the increase of blood pressure, mainly the amount and quality of dietary fat, being the intake of saturated fatty acids and cholesterol an important risk factor in the development of hypertension. However, the relationship between dietary fat, gut microbiota and hypertension has been scarcely studied. Previous results of our laboratory have demonstrated a link between changes in gut microbiota, BP and high fat diets. Mice fed with a diet enriched with butter (20%) increased its BP levels and visceral adiposity compared with control; and different fats had different effects on gut microbial composition (Hidalgo et al., 2014). The levels of Enterococcus faecalis in fecal samples of these animals, showed a linear positive correlation with BP at the end of the experiment. When mice fed with a standard chow diet were inoculated with E. faecalis 12M3-5 during six weeks, the levels of BP were higher than controls, but they did not develop obesity (Prieto et al, 2015). In the present work, we analyze the relationship between the increase in the BP of mice inoculated with E. faecalis 12M3-5 and the changes in urine nitric oxide and 8-isoprostane. Male Swiss Webster mice were divided in two groups: One Group were inoculated daily with a sample of E. faecalis 12M3-5 (Enterococcus group), and the other received a placebo (Control group). After six weeks of experiment, BP data were measured. Animals were placed into individual metabolic cages in order to determine water intake and diuresis. Urine samples were taken to measure Nitric Oxide and 8-isoprostane levels. Blood pressure was 19% higher in Enterococcus than in control group (211±10,3 vs 177±7,8 mmHg; p<0,5). Water intake (3,3±0,43 vs 7,0±1,30 mL/day; p<0,05) and diuresis (1,2±0,16 vs 2,4±0,71 mL/day) were lower in Enterococcus animals, although no significant differences were reached in urine excretion. No differences were also found in urine Nitric Oxide (70,2±8,48 vs 51,8±15,98 μM/L), but a significant high level of 8-isoprostanes was measured in the urine of Enterococcus group (595,3±23,18 vs 476,3±40,76 pg/mL; p<0,05). These results indicate that the hypertensive effect of E. faecalis 12M3-5 does not seem to be due to natriuresis or enhanced renal nitric oxide synthesis. However, the increased levels of 8-isoprostane in urine will be related to an increased lipid peroxidation in animals inoculated with Enterococcus.

Where applicable, experiments conform with Society ethical requirements