Cerebral aqueduct block attenuates cardio-renal injuries in post-DOCA-NaCl-hypertensive Dahl R rats.

The systemic and/or local effects of the hydrocephalic brain were investigated in DOCA-NaCl-hypertensive Dahl R rats induced by 250 mg kg(-1) DOCA in silicone and 1% saline water. After a 1-week recovery with 0.3% NaCl chow and tap water, one group had the aqueduct of Sylvius blocked with silicone and epoxy materials with a control sham group matching mean blood pressure (BP) and body weight. The 4-week-postsurgery BP on the 0.3% NaCl diet averaged 161±3.2 in the sham group and 146±2.3 mm Hg in the blocked group (P<0.0001). Both groups were then given an 8% NaCl diet and after 4 weeks, the sham group's BP was increased further with markedly increased mortality: 186 mm Hg vs. 154 mm Hg (P<0.0001); 12 sham rats died after 11 weeks, while all the blocked rats survived (P<0.0001). A transient change in plasma Na levels was observed in the blocked group after 48 h on the 8% NaCl diet. At 14 weeks, 0 sham rats survived, compared with 10 out of 16 blocked rats (P<0.0001). After 11 weeks on 8% NaCl, the average tail venous pressure in the sham group was significantly higher than that of the blocked rats (P<0.0001) indicating the end stage of renal and heart failure. The hearts and kidneys weighed significantly more in the sham vs. the blocked rats (P<0.0001 for both groups). These results indicate that the aqueduct block prevents post-DOCA hypertension and cardio-renal injuries, suggesting that centralized third ventricular brain signaling has a role in salt-genetic hypertension.