Persistent antihypertensive effect of oral nitrite supplied up to one year via the drinking water in spontaneously hypertensive rats.

The hypothesis was studied whether the chronic administration of nitrite lowers the blood pressure of spontaneously hypertensive rats (SHR) and prevents secondary hypertension-induced organ lesions. For this purpose totally 96 SHR received 50 to 75 mmol/l NaNO 2 or equimolar amounts of NaHCO 3 in their drinking water during 4, 8 or 12 months. At each point of time arterial blood pressure, determined with the tail cuff method, was significantly lower in the NaNO 2 -group in comparison to the controls indicating that no significant tolerance towards nitrite had developed. There was also a tendency towards reduced cardiac hypertrophy and renal atrophy in the NaNO 2 -group, however without reaching the level of significance. Drinking water containing 75 mmol NaNO 2 /l was not well tolerated by young rats in contrast to 50 mmol/l. Possible beneficial effects of high dietary nitrate/nitrite levels are discussed with respect to the low frequency of hypertension observed in vegetarians.