Protective effects in ambulatory blood pressure and centralized injuries in hydrocephalic Dahl rats on high and low NaCl diets.

Our previous studies in hydrocephalic Dahl rats indicated that the NaCl signal is perceived in the structures around the third brain ventricle. In the present study, we assessed 24-h ambulatory blood pressures (ABPs), weight (WT) gains, and the kidney and brain injuries in induced hydrocephalic and control group Dahl S rats on 0.3% and 6% NaCl diets. Constant WT gains were observed among low NaCl fed and high NaCl fed aqueduct blocked groups, whereas high NaCl-fed sham group rats were losing WT and dying off after 8 weeks. A circadian BP curve in the high NaCl sham group was very distinct from that in the other three groups with markedly increased peak pressure during the light cycle with very high amplitude as compared with all the other three groups (both P <.0001). There was not only a very unstable fluctuating curve present, but a day-night rhythm shift was also prominent in the high NaCl sham group. In a kidney cross-section, 54 rats on a 0.3% low NaCl diet for 14 weeks averaged 156 glomeruli. A total of 34 high NaCl fed, aqueduct blocked rats averaged 141 glomeruli, whereas 23 sham blocked rats averaged 102 glomeruli (-28%, P <.0001). A brain cross-section showed many small lacunae in high NaCl-fed sham rats as compared with the truly blocked rats (193 +/- 14 v 77 +/- 10 lacunae, a 2.5-fold reduction, P <.0001). The changes in the blocked group may be due to volume and electrolyte rebalance with reduced pressures in the brain volume-controlling center.