Interaction between calcium and cadmium in the 1,25-dihydroxyvitamin D3 stimulated rat duodenum.
Toxicol Appl Pharmacol 1984 Aug; 75(1):98-104
The interaction between calcium (7440702) and cadmium (7440439) was investigated in rat duodenum. Male Sprague-Dawley-rats were maintained on a diet adequate in vitamin-D (1406162), calcium, and phosphorus (7723140); temperature, humidity and light were controlled. The vitamin-D metabolite 1,25-dihydroxyvitamin-D3 was administered intraperitoneally at 0.5 microgram per 50 microliters 4 hours prior to intestinal transport measurements; the control rats were given vehicle alone. The intestinal transport of calcium and cadmium was measured with everted duodenal sacs using appropriate biological solutions. Tritiated polyethylene-glycol was used as a non absorbable volume marker. For transport of calcium, labeled calcium-45 was employed; for cadmium, labeled cadmium-109 was employed. Unlabeled calcium or cadmium was included in duodenal mucosal bathing solution only when used to inhibit the transport of the other. Radionuclides were counted in a programmed scintillation spectrometer. The ratio of serosal to mucosal calcium concentration was initially maintained to be 1. Alterations of this ratio were evaluated experimentally. During the 60 minutes of incubation, calcium was actively transported and further enhanced by the vitamin- D metabolite; the serosal to mucosal ratio was 3.35. Cadmium at a 10 micromolar concentration abolished the stimulatory effect of the vitamin-D metabolite. Cadmium at a 100 micromolar dose completely blocked the active transport. Cadmium uptake and transport were not altered by the vitamin-D metabolite; cadmium accumulation in mucosal tissue was significantly inhibited by calcium at 1 millimolar concentration. The authors conclude that the interaction between calcium and cadmium in the duodenal mucosa is related to the action of cadmium in blocking active transport processes.
NIOSH-Author; Medical-research; Animal-studies; Heavy-metals; Drug-interaction; Quantitative-analysis; Toxicology; Radiochemical-analysis; Transport-mechanisms; Cell-wall-permeability; Biological-effects
7440-70-2; 7440-43-9; 1406-16-2; 7723-14-0
Toxicology and Applied Pharmacology