Attenuation of blood pressure increases in Dahl salt-sensitive rats by exercise

Systolic blood pressure was determined weekly to assess the development of hypertension in sedentary and active Dahl salt-sensitive (S) rats that were exercised by running at 20 m/min, 60 min/day, 5 days/wk. The marked rise in blood pressure that occurred with feeding 8% NaCl (wt/wt) diet in Dahl S rats could be attenuated by chronically practiced endurance running, but only if exercise at 20 m/min was started at the beginning of salt feeding. Under the same dietary feeding conditions, running at 27 m/min resulted in incomplete attenuation of hypertension. Further, running for 30 min/day was not as beneficial as running 60 min/day at 20 m/min. Delaying the start of exercise for 6 wk after the beginning of salt feeding did not result in reduction of hypertension in the S rat. These experiments indicate that increases in blood pressure can be prevented in Dahl S rats for 12 wk if running is initiated concomitantly with salt feeding. Blood pressure is not reduced if hypertension due to salt feeding has been continued for 6 wk. The results also indicate that there is an optimal exercise intensity, duration, or both, for controlling hypertension in Dahl rats.