摘要：To investigate the direct effect of cadmium on the bone metabolism, tibia from 9-day chick embryo was cultivated for six days by Roller-tube method and CdCl2 was added into the culture medium in 5 to 30 ppm concentration range. Cartilage ends and bone shafts were analyzed for bone matrix formation and calcification by measuring the chondroitin sulfate, hydroxyproline, inorganic phosphate and cadmium content and alkaline phosphatase activity. Both bone matrix content and alkaline phosphatase activity in two parts of the bone decreased with increasing the concentration of CdCl2, although the rate of inhibition of cadmium was stronger to alkaline phosphatase than to the increase of matrix content. Cartilage ends and bone shafts were found to differ in mineral content of cadmium-treated bone unlike matrix content and alkaline phosphatase activity, as inorganic phosphate content of bone shafts in the presence of CdCl2 were similar to control though those of cartilage ends were less than control. Cadmium content of cartilage ends per dry weight linearly increased with the increase of cadmium concentration while that of bone shafts exponentially increased. Histopathological examination of the tibia cultured with medium containing CdCl2 showed that in bone shafts the formation of bone matrix was inferior to control and the ossification remained nearly in the state before culture. These results suggest that cadmium inhibits the bone matrix formation and brings about a damage to the ossification although cadmium unaffects the bone mineral deposition.
