Salt-sensitive and carbohydrate-sensitive rodent hypertension: evidence of strain differences

It is well-established that diets enriched either with salt or simple sugars are associated with variable increases in blood pressure, but the interrelationship between carbohydrate- and salt-sensitive hypertension has received comparatively little attention. The effects of varying salt intake on blood pressure responses to a fructose-enriched diet were examined in a variety of common laboratory rat strains. Sprague-Dawley, Fischer 344, and Wistar rats were placed on diets enriched in fructose, salt, or a combination of both for 12 days. Measurements of blood pressure (tail-cuff) and fasting plasma insulin concentrations were recorded before and after dietary intervention. In response to the fructose-enriched diet (normal salt), all strains developed a significant increase in plasma insulin (1-2 fold, p < 0.05). However, only Sprague-Dawley rats showed an increase in blood pressure in response to the fructose-enriched diet (21 mmHg, p < 0.05). A high salt diet increased blood pressure only in Fischer 344 rats (10 mmHg, p < 0.05), but the combination of high fructose and high salt increased blood pressure significantly in both Fischer 344 and Wistar rats (mean of 19 mmHg, p < 0.05). In conclusion, the ability of a fructose-enriched diet to increase blood pressure varies as a function of strain, and can be modulated by changes in salt intake.