Impact of recurrent dehydration with mild periodic water restriction on blood pressure and renal function in male spontaneously hypertensive rats.

The kidneys regulate fluid balance but are susceptible to adverse effects of inadequate hydration. Epidemiological studies have linked low water intake to renal dysfunction and chronic kidney disease. Previously we showed that restricting water intake to a single 2-h period daily for 4 weeks promotes hypertension as well as renal inflammation, fibrosis and dysfunction in male spontaneously hypertensive rats (SHR). Building on these findings, the aim of the present study was to determine whether a milder, more intermittent dehydration protocol (two 1-h periods of water access per weekday plus free access on weekends for 8 weeks) would affect renal function, renal fibrosis and inflammation, and blood pressure in the same rat model. We hypothesised that this protocol would maintain renal function, limit renal fibrosis and inflammation, and avoid further exacerbation of hypertension in male SHR. Our findings showed that the mild water restriction protocol resulted in cyclic changes in urine osmolarity, indicating periods of dehydration and rehydration. However, it did not exacerbate hypertension, accelerate renal dysfunction or increase proinflammatory processes in the kidneys. These results suggest that mild recurrent dehydration does not produce the same adverse effects observed under stricter water restriction and that the impact of recurrent dehydration on chronic kidney disease progression may depend on the severity and pattern of water restriction.