Aqueduct block markedly reduces mortality and hypertension in post-deoxycorticosterone acetate Dahl salt-resistant rats.

Abstract

When Dahl salt-resistant (DR) rats are given mild post-deoxycorticosterone acetate (DOCA) hypertension, they will have, within 8 weeks, a 53% mortality on a high NaCl diet, without a rise of blood pressure. Forty-two DR rats were given DOCA in silicone (250 mg/kg) and 1% NaCl to drink. After 4 weeks, the DOCA and 1% saline were removed and replaced with a low NaCl diet and tap water. One week later, they were divided into two groups perfectly matched for blood pressure (154 mm Hg). One group had the aqueduct of Sylvius blocked with silicone and epoxy materials; the other group had a sham block. After 4 more recovery weeks on a low NaCl diet, blood pressure averaged 171 mm Hg in sham rats and 147 mm Hg in truly blocked rats (p less than 0.0001). Thus, the aqueduct block prevented most of the post-DOCA hypertension and permitted a strong post-DOCA recovery from the acute DOCA hypertension. The rats with the sham block had an actual rise in blood pressure during the post-DOCA recovery period. The vicious cycle leading to permanent post-DOCA NaCl hypertension was broken by the aqueduct block. Then both groups began an 8% high NaCl diet, and after 4 weeks, blood pressure averaged 184 mm Hg in sham and 155 mm Hg in truly blocked rats (p less than 0.0001). After 12 weeks on 8% NaCl, all sham rats had died (28 of 28), whereas only one of 14 truly blocked rats had died (93% reduction in mortality, p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)