Abstract P400: Effects Of Time Restricted Feeding On Blood Pressure And Urine Output

Abstract

Americans consume ~48% more salt than the recommended daily intake, increasing the sodium load placed on the kidneys. Normally, the kidneys excrete this excess sodium, however salt-sensitive (SS) individuals are unable to do so and develop hypertension. Time-restricted feeding (TRF), in which food is consumed in <10 hours, has been shown to improve various cardiometabolic disorders, however there is limited research on its effect in SS hypertension. The goal of this study was to determine if intermittent salt consumption via TRF can improve SS hypertension in the Dahl SS rat model. Male (n=7-9/group) and female (n=4/group) SS rats were randomly divided into the following groups: low salt ad libitum (LS ad lib), low salt TRF (LS TRF), high salt ad libitum (HS ad lib), or high salt TRF (HS TRF) and underwent a two-week protocol. During the first week, all rats had ad libitum access to their respective diet to establish hypertension in the HS groups. During the second week, some animals began TRF, in which food was provided for 8 hours during the active period (2200-0600 hrs), and metabolic phenotypes were assessed in all rats using the Promethion (Sable Systems). Urine was collected for 8-9 hrs after the feeding period. Prior to endpoint, anesthetized blood pressure was measured at the end of the fasting period. We found that the HS TRF group had reduced systolic blood pressure in both males (138.69 ± 4.29 mmHg vs 143.33 ± 7.43 mmHg; mean ± SEM) and females (129.19 ± 6.29 mmHg vs 135.85 ± 10.88 mmHg; mean ± SEM) compared to the HS ad lib group, however this was not significant. Urine excretion was significantly higher in the HS TRF group compared to the HS ad lib group in both males (8.89 ± 1.06 mL vs 4.06 ± 0.42 mL; mean ± SEM; p<0.05) and females (7.5 ± 0.20 mL vs 4.88 ± 0.43 mL; mean ± SEM; p<0.05). Furthermore, while the rats were in the Promethion, there was a higher amount of water loss (VH 2 O; which can include evaporated urine) in the HS TRF group compared to the HS ad lib group during the fasting period in both males (1.52 ± 0.03 g/hr vs 1.40 ± 0.03 g/hr; mean ± SEM; p<0.05) and females (1.18 ± 0.03 g/hr vs 0.96 ± 0.01 g/hr; mean ± SEM; p<0.05). Overall, these results may suggest that TRF produces a diuretic effect in the Dahl SS rat model, however further studies are required to confirm this.