Identification of the Gastrointestinal Absorption Site for Cadmium Chloride in Vivo

Abstract

Most models for the study of the mechanism of intestinal absorption of Cadmium (Cd) have been using intestinal tissue in vitro or in situ. The in vivo experiments reported in this article were performed in an attempt to localize the site for gastrointestinal absorption of cadmium chloride during natural physiological conditions by oral exposure of mice to 109Cd-labelled CdCl2. Independent of exposure via drinking water or oral administration of a single dose, Cd was primarily deposited in the most proximal duodenum. Thus the present study as well as others indicate that absorption takes place in the proximal part of the intestine. Absorbed Cd is initially transported to the liver and deposited before being redistributed and accumulated in the kidneys. In this experimental model, dietary tetraethylthiuram disulfide exposure was shown to change the intestinal labelling profile and increase the whole-body retention as well as the intestinal deposition of Cd.

Bioavailability of cadmium from infant diets in newborn rats

“…This is about ten times higher than the previously reported 6% (EngstroÈ m and Nordberg 1978) and 5% (Lind and Wicklund Glynn 1997) whole-body retention in adult mice 3 and 5 days, respectively, after a single oral dose of 109 CdCl 2 in water. Even lower (1%) whole-body retention was reported by Sùrensen et al (1993), also in adult mice 3 days after a single oral 109 CdCl 2 dose. EngstroÈ m and Nordberg (1979) did not ®nd any dierences in the fractional absorption and retention of Cd in mice given oral doses in the range 15 to 750 lg/kg body weight.…”

“…By 6 h after a single oral dose of 0.005 or 5 lg Cd/kg body weight to adult mice, 61% and 42% of the dose, respectively, were located in the ®rst 5-cm segment of the rinsed small intestine (Lind and Wicklund Glynn 1997). Approximately 75% of the total gastrointestinal deposition was located in the ®rst 8 cm of the rinsed intestine of adult mice 24 h after a single oral dose of 109 Cd (Sùrensen et al 1993). This is most likely explained by the low pH of the gastric contents emptying into the duodenum (Andersen et al 1992;Taguchi 1985).…”

“…In adult humans the absorption is approximately 5% (WHO 1992). The site of gastrointestinal uptake has been studied in adult mice by Sùrensen et al (1993) and Andersen et al (1994), who found a high deposition of Cd in the duodenum, indicating that this is probably the major site of absorption. The bioavailability of Cd from food is dependent on the composition of the diet and on the age and nutritional status of the individual.…”

Bioavailability of cadmium from infant diets in newborn rats

“…This is about ten times higher than the previously reported 6% (EngstroÈ m and Nordberg 1978) and 5% (Lind and Wicklund Glynn 1997) whole-body retention in adult mice 3 and 5 days, respectively, after a single oral dose of 109 CdCl 2 in water. Even lower (1%) whole-body retention was reported by Sùrensen et al (1993), also in adult mice 3 days after a single oral 109 CdCl 2 dose. EngstroÈ m and Nordberg (1979) did not ®nd any dierences in the fractional absorption and retention of Cd in mice given oral doses in the range 15 to 750 lg/kg body weight.…”

“…By 6 h after a single oral dose of 0.005 or 5 lg Cd/kg body weight to adult mice, 61% and 42% of the dose, respectively, were located in the ®rst 5-cm segment of the rinsed small intestine (Lind and Wicklund Glynn 1997). Approximately 75% of the total gastrointestinal deposition was located in the ®rst 8 cm of the rinsed intestine of adult mice 24 h after a single oral dose of 109 Cd (Sùrensen et al 1993). This is most likely explained by the low pH of the gastric contents emptying into the duodenum (Andersen et al 1992;Taguchi 1985).…”

“…In adult humans the absorption is approximately 5% (WHO 1992). The site of gastrointestinal uptake has been studied in adult mice by Sùrensen et al (1993) and Andersen et al (1994), who found a high deposition of Cd in the duodenum, indicating that this is probably the major site of absorption. The bioavailability of Cd from food is dependent on the composition of the diet and on the age and nutritional status of the individual.…”

Biological levels of cadmium and zinc in the small intestine of non-occupationally exposed human subjects

“…In mice exposed per os to a single dose of radioactive Cd, the highest radioactivity was observed in the duodenum with longitudinally decreasing radioactivity from the duodenum to the ileum. 8 From regressions shown in Figure 2A /D it may be deduced that, probably, there are two fractions of intestinal Cd: a) a pool of Cd correlating with total body Cd, which is probably more stable bound in intestinal cells; b) a pool of Cd corresponding to actual intake of Cd via food, which may be further absorbed into blood or eliminated through faeces. Quantitatively, this fraction may correspond to the constant value in regression equations (0.13 l g/g for duodenum and 0.05 l g/g for ileum; Figure 2).…”

Cadmium

“……”

Bioavailability of cadmium from infant diets in newborn rats

“…This is about ten times higher than the previously reported 6% (EngstroÈ m and Nordberg 1978) and 5% (Lind and Wicklund Glynn 1997) whole-body retention in adult mice 3 and 5 days, respectively, after a single oral dose of 109 CdCl 2 in water. Even lower (1%) whole-body retention was reported by Sùrensen et al (1993), also in adult mice 3 days after a single oral 109 CdCl 2 dose. EngstroÈ m and Nordberg (1979) did not ®nd any dierences in the fractional absorption and retention of Cd in mice given oral doses in the range 15 to 750 lg/kg body weight.…”

“…By 6 h after a single oral dose of 0.005 or 5 lg Cd/kg body weight to adult mice, 61% and 42% of the dose, respectively, were located in the ®rst 5-cm segment of the rinsed small intestine (Lind and Wicklund Glynn 1997). Approximately 75% of the total gastrointestinal deposition was located in the ®rst 8 cm of the rinsed intestine of adult mice 24 h after a single oral dose of 109 Cd (Sùrensen et al 1993). This is most likely explained by the low pH of the gastric contents emptying into the duodenum (Andersen et al 1992;Taguchi 1985).…”

“…In adult humans the absorption is approximately 5% (WHO 1992). The site of gastrointestinal uptake has been studied in adult mice by Sùrensen et al (1993) and Andersen et al (1994), who found a high deposition of Cd in the duodenum, indicating that this is probably the major site of absorption. The bioavailability of Cd from food is dependent on the composition of the diet and on the age and nutritional status of the individual.…”

Biological levels of cadmium and zinc in the small intestine of non-occupationally exposed human subjects

“…In mice exposed per os to a single dose of radioactive Cd, the highest radioactivity was observed in the duodenum with longitudinally decreasing radioactivity from the duodenum to the ileum. 8 From regressions shown in Figure 2A /D it may be deduced that, probably, there are two fractions of intestinal Cd: a) a pool of Cd correlating with total body Cd, which is probably more stable bound in intestinal cells; b) a pool of Cd corresponding to actual intake of Cd via food, which may be further absorbed into blood or eliminated through faeces. Quantitatively, this fraction may correspond to the constant value in regression equations (0.13 l g/g for duodenum and 0.05 l g/g for ileum; Figure 2).…”

Cadmium

“……”

Bioavailability of cadmium from infant diets in newborn rats

“…This is about ten times higher than the previously reported 6% (EngstroÈ m and Nordberg 1978) and 5% (Lind and Wicklund Glynn 1997) whole-body retention in adult mice 3 and 5 days, respectively, after a single oral dose of 109 CdCl 2 in water. Even lower (1%) whole-body retention was reported by Sùrensen et al (1993), also in adult mice 3 days after a single oral 109 CdCl 2 dose. EngstroÈ m and Nordberg (1979) did not ®nd any dierences in the fractional absorption and retention of Cd in mice given oral doses in the range 15 to 750 lg/kg body weight.…”

“…By 6 h after a single oral dose of 0.005 or 5 lg Cd/kg body weight to adult mice, 61% and 42% of the dose, respectively, were located in the ®rst 5-cm segment of the rinsed small intestine (Lind and Wicklund Glynn 1997). Approximately 75% of the total gastrointestinal deposition was located in the ®rst 8 cm of the rinsed intestine of adult mice 24 h after a single oral dose of 109 Cd (Sùrensen et al 1993). This is most likely explained by the low pH of the gastric contents emptying into the duodenum (Andersen et al 1992;Taguchi 1985).…”

“…In adult humans the absorption is approximately 5% (WHO 1992). The site of gastrointestinal uptake has been studied in adult mice by Sùrensen et al (1993) and Andersen et al (1994), who found a high deposition of Cd in the duodenum, indicating that this is probably the major site of absorption. The bioavailability of Cd from food is dependent on the composition of the diet and on the age and nutritional status of the individual.…”

Biological levels of cadmium and zinc in the small intestine of non-occupationally exposed human subjects

“…In mice exposed per os to a single dose of radioactive Cd, the highest radioactivity was observed in the duodenum with longitudinally decreasing radioactivity from the duodenum to the ileum. 8 From regressions shown in Figure 2A /D it may be deduced that, probably, there are two fractions of intestinal Cd: a) a pool of Cd correlating with total body Cd, which is probably more stable bound in intestinal cells; b) a pool of Cd corresponding to actual intake of Cd via food, which may be further absorbed into blood or eliminated through faeces. Quantitatively, this fraction may correspond to the constant value in regression equations (0.13 l g/g for duodenum and 0.05 l g/g for ileum; Figure 2).…”

Cadmium

“……”