[Study on cadmium load and calcium deficit]

The effects of cadmium given by intraperitoneal injection on calcium absorption and calcium balance in rats were investigated. The results showed that intestinal calcium absorption rate decreased steadily with increasing cadmium load. When the cadmium load exceeded 9.0 mg, the average calcium absorption fell into negative value and thus led most of the rats to calcium deficit. It suggested that the negative calcium balance in rats was caused mainly by way of fecal excretion rather than the urinary route, since the calcium loss via the intestinal tract surpassed that via the urinary tract. The excess of urinary calcium (hypercalciurea), which appeared concurrently with that of feacl one's has, however, the same significance of indicating the calcium loss, so it can be referred to an indicator of calcium deficit. Our results gave no support to the view that calcium deficit and skeletal lesion were resulted from the calcium loss by urinary way. In the study, we found that there was negative correlation between cadmium burden and calcium balance, and there was remarkable dose-response relationship between cadmium burden and the rate of calcium deficit.