Short-Term NOS II Inhibition Leads to Long-Term Salt-Sensitivity in Dahl Salt-Resistant Rats
We have previously shown that inhibition of inducible nitric oxide synthase (NOS II) evokes a salt-sensitive increase in blood pressure in Dahl salt-resistant rats when given a high salt (8% NaCl) diet for 7 days. To determine whether or not the effect of NOS II inhibition is short-lived, we continued the high salt diet for an additional 3 weeks following the discontinuation of the NOS II inhibitor. DR rats were given one of two NOS II selective inhibitors, AMT (300 nmoles/hr) and 1400W (35 nmoles/hr) for 2 weeks. A high salt diet was initiated after the first week of NOS II inhibition and continued for an additional 3 weeks for a total of 4 weeks of high salt treatment. Control DR rats received high salt alone for 4 weeks. Systolic blood pressure was taken at baseline and once weekly for the treatment period. Blood pressure significantly increased in DR rats after 1 week of high salt following NOS II inhibition. The blood pressure remained elevated throughout the 4-week period of high salt treatment despite the discontinuation of NOS II inhibitors 1 week following the initiation of the high salt diet. There was no significant change in blood pressure in DR rats on high salt diet alone. These data suggest that salt-sensitive hypertension can be evoked by transient NOS II inhibitor exposure. We conclude that tranisent NOS II inhibition may initiate events or processes that high salt maintains leading to sustained elevation in systolic blood pressure.