Genetic influence on cadmium-induced hypertension.

Dahl hypertension-resistant (R) and hypertension-sensitive (S) rats were used to determine whether cadmium-induced hypertension is dependent on genetic predisposition. In experiment I, 16 wk-old R and S rats of both sexes were injected with two doses of cadmium (1 and 2 mg/kg body wt, ip), whereas the controls received the same volumes of saline. Hypertension and renal vascular changes were observed in cadmium-injected S rats but not in R rats. The S females appeared more sensitive than S males to the hypertensinogenic effect of cadmium. In experiment II, groups of weanling female R and S rats were given 0, 1, 2.5, 5, or 10 mg cadmium/liter drinking water and fed either a low-salt (0.4% NaCl) or a high-salt (4% NaCl) diet for 28 wk. Cadmium produced cardiac hypertrophy (1 mg cadmium/liter) and hypertension associated with renal vascular changes (1--5 mg cadmium/ liter), and it enhanced proteinuria (1-10 mg cadmium/liter) in S rats on a low-salt diet. Also, the development of salt-induced hypertension was accelerated in cadmium-fed (1 and 2.5 mg/liter) S rats. These adverse effects of cadmium were not detected in R rats on either salt diet. In experiments I and II, cadmium concentrations in the kidneys and liver of S rats were higher (P less than 0.001) than in those of R rats. These data indicate that genetic differences influence the pathogenesis of cadmium-induced hypertension.