Sodium retention in rats with cadmium-induced hypertension.

Chronic feeding of non-toxic doses of cadmium induces an average increase of 15 to 20 mm Hg in indirectly measured systolic pressure of lightly anaesthetized rats. The mechanism of this increase is not known, but cadmium has several potentially pressor effects, including increased sodium retention. This report describes both sodium balance and blood pressure in a pair of experiments where cadmium was fed and in a pair where it was injected. All four cadmium challenges induced sodium retention and also induced hypertension. Thus, rats with either low or moderate chronic exposure to fed cadmium (well below the exposures required to induce toxicity) retained more intraperitoneally injected radiosodium than controls and at the same time developed higher systolic pressures than controls. Immediately following intraperitoneally injected cadmium, rats lost a radiosodium more rapidly than controls; in both situations the blood pressure was higher than the controls. These data indicate that some of the pressor effect associated with cadmium exposure could result from its concomitant antinatriuretic effect.