Arzneimittelforschung. 1995 Mar; 45(3): 258-61.

Antihypertensive effect of oral nitrite uptake in the spontaneously hypertensive rat.

Beier S, Classen HG, Loeffler K, Schumacher E, ThÃ¶ni H.

Department of Pharmacology and Toxicology of Nutrition, University of Hohenheim, Stuttgart, Germany.

The lower blood pressure of vegetarians might partly be due to the high dietary load with nitrate which--to a certain extent--is further reduced to nitrite and finally to nitric oxide. To test this hypothesis, spontaneously hypertensive rats received drinking water containing 0, 25, 50 or 100 mmol/l NO2 during 56 days. Food was offered ad libitum or was restricted by 20% (pair-feeding) to simulate the lower energy consumption of vegetarians. Blood pressure, which was monitored at regular intervals, was lowered in a dose-dependent manner by nitrite. This effect was reversible and could not be enhanced by energy restriction. In volunteers plasma nitrate levels increased by a factor of 8 to 32 following the ingestion of a nitrate-rich meal, and mean methemoglobin concentrations increased from 1.2% to 2.4% indicating the endogenous formation of nitrite under these conditions.