Reduction of Salt Sensitivity in Stroke-Prone Spontaneously Hypertensive Rats Administered an AT1 Receptor Antagonist During Suckling

BACKGROUND: In this study, antihypertensive therapy was started during suckling and the effect on blood pressure (BP) and salt sensitivity of stroke-prone spontaneously hypertensive rats (SHRSP) was determined. METHODS: The SHRSP were treated with an AT1 receptor antagonist (losartan: 100 mg/L in drinking water) from 2 to 4 weeks of age. After stopping treatment at 4 weeks of age, the control group and the losartan group were fed a commercial diet with tap water ad libitum until 10 weeks of age. Both the control and losartan groups were switched to 1% saline at the age of 10 weeks. RESULTS: Salt loading was started at 10 weeks of age, with BP levels of 203+/-3 and 199+/-6 mm Hg for the control group and the losartan group, respectively, at that age. After 4 weeks of salt loading, BP levels were 253+/-7 mm Hg in the control group and 242+/-5 mm Hg in the losartan group, showing a mild elevation in the losartan group. The life span of the losartan group (104+/-78 days) was significantly greater than that of the control group (37+/-17 days). Plasma aldosterone concentrations of the losartan group were lower than those of the control group at 4 and 15 weeks of age. CONCLUSIONS: We have demonstrated the renin-angiotensin-aldosterone system may play a key role in the establishment of end-organ salt sensitivity, and the period of lactation in critical for salt sensitivity in later life.