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.