BackgroundReduction in sodium intake improves the survival of stroke-prone spontaneously hypertensive rats (SHR-SP) without causing any change in their blood pressure.ObjectiveTo investigate whether the diuretic indapamide improves survival of SHR-SP and whether changes in the structure and the function of large arteries are associated with survival.Experimental designForty-eight hypertensive rats aged 6 weeks were divided into three groups: a control SHR-SP group (n = 24) and a control spontaneously hypertensive rat (SHR) group (n = 12), with 1% saline drinking water; and an indapamide-treated SHR-SP group (n = 12) with 1% saline drinking water administered 1 mg/kg per day indapamide via their food. At the end of a 12-week follow-up period, pulsatile changes in blood pressure and common carotid artery diameter (measured by high-resolution echo-tracking techniques) were determined and aortic histomorphometry was performed.ResultsBy the end of the study 58% of the SHR-SP control group rats had died. There were no deaths in the other two groups. In these two groups the mean blood pressure (217 ± 10 and 212 ± 7 mmHg), carotid diameter and distensibility (0.48 ± 0.09 and 0.61 ± 0.22 mmHg-1), arterial thickness (116 ± 4 and 116 ± 3 μm), and collagen content of the arterial wall were identical. In the SHR-SP control group the mean blood pressure was significantly lower (168 ± 9 mmHg), the carotid distensibility was higher (1.47 ± 0.35 mmHg-1), and the arterial thickness (138 ± 5 μm) and collagen content were substantially higher than those in the other two groups. In the study population as a whole, for a given mean arterial pressure the carotid distensibility was identical in the three groups, although the arterial thickness was substantially greater in the SHR-SP control group rats.ConclusionsThe study provides evidence that the diuretic compound indapamide improved the survival of SRH-SP even though their blood pressure was higher than that of untreated animals, and that genetic sensitivity to sodium, rather than blood pressure, influences the changes in arterial structure.