Since the body weight (bw) of SHR was reduced when compared to Wistar rats, the SFR was normalized to the weight of the animals. Increased SFR ( Fig. 1) was observed in 12-week-old when compared to 4-week-old Wistar rats. Any alteration on SFR was observed between 4 and 12 weeks SHR. SHR at 12-week-old showed a reduced SFR than Wistar rat at same age. A slight increase in saliva pH value in SHR 12 weeks old rats was observed when compared to Wistar rat at same age (Table 1). As body weight and SFR were reduced in SHR, all results of biochemical analysis were normalized to the SFR based on body weight. A reduced SBC was

observed only in 12-weeks-old Wistar rats when compared selleck to other groups (Table 1). The saliva IgA concentration was not different between groups (Table 1). Protein concentration in the saliva and specific amylase activity were not altered by growth in Wistar group (Fig. 2 and Fig. 3). In SHR, the total protein concentration in saliva showed a threefold increase in 12-week-olds when compared with 4-week-olds (Fig. 2), associated

to an increase of the specific amylase activity (Fig. 3) in these animals.[Ca++] was increased in the saliva of 12-week-old Wistar when compared to 4-week-old rats (Fig. 4). A reduced [Ca++] was observed in SHR when compared to Wistar at 12 weeks (Fig. 4). The [F−] was Smad inhibitor higher in 12 than 4 weeks old Wistar rats and in SHR group (Fig. 5). The fluoride concentration in water and food was 0.068 ppm (mg F/L, average of samples) and 18.21 mg F/kg, respectively. By assessing the amount of daily fluoride (mg F) intake per body weight (kg) of each animal during 12 weeks, we observed that Wistar and SHR ingested the same quantity of fluoride (Wistar, 1.56 mg F/kg/day; SHR, 1.57 mg F/kg/day). In this study, the SHR was used as experimental model of hypertension, since the haemodynamic characteristics of the SHR are very similar to those of human essential arterial hypertension. These animals are born normotensive with

average arterial pressure around 112 mmHg and develop spontaneously an increase in arterial pressure from the 8th week after birth7 reaching values higher than 150 mmHg at 12 weeks of age. It has been widely accepted that the most appropriate control strain to SHR studies is the Wistar-Kyoto (WKY) rat, to which SHR rats are genetically oxyclozanide related. Concerns have been raised about genetic differences8 and biological variability9 between SHR and WKY rats. Moreover, evidence suggest that the WKY strain is not the most suitable for backcross studies because of the incidence of spontaneous hypertension and the somewhat higher levels of blood pressure in these rats.10, 11, 12 and 13 According to several studies,4, 14 and 15 SHRs were compared to Wistar rats, which are safely normotensive and with no genetic alteration that could modulate arterial pressure. In this study, SHR showed lower body weight compared to the normotensive controls, regardless of the age evaluated.