Failure to produce hypertension in rats by chronic exposure to cadmium.

Groups of ten male and ten female Sprague-Dawley rats were exposed for 92 and 84 wk, respectively, to increasing concentrations of cadmium (as the chloride) in their drinking-water. The exposure levels of Cd used were 0, 5, 12.6 and 31.5 ppm Cd, and 5 ppm Cd plus certain trace metals. Blood pressure was measured in unanaesthetized animals at regular intervals (46 times in females, 49 times in males) by an indirect method to which the animals were kept conditioned. At the end of the experiments blood pressure was also determined directly under sodium pentobarbital anaesthesia. Although the weight of the kidneys, Cd residues and the severity of histological alterations in the kidneys increased in a dose-related manner, the blood pressure and pulse rate were not significantly affected in any of the experimental groups. There was a dose-dependent decrease in water consumption; all other parameters remained unaffected.