Cadmium accumulation in aortas of smokers

Abdominal aortic aneurysm is a smoking-related disorder. Cadmium, inhaled f rom cigarettes, may accumulate in the aorta and facilitate weakening of the aorta through adverse effects on smooth muscle cell metabolism Cadmium was measured by atomic absorption spectrometry in infrarenal aortas from 13 pa tients with abdominal aortic aneurysm and from 17 age- and sex-matched pati ents with normal-diameter abdominal aorta. Total cadmium content was associ ated with smoking, assessed as pack-years (r=0.54, P=0.004), but was simila r in aneurysmal and undilated aortas. The cadmium content (mean+/-SE) was h igher in the media (3.25+/-0.53 ng/mg dry wt, 7+/-1.2 mu mol/L) than in the intima or adventitia (1.14+/-0.24 and 1.87+/-0.38 ng/mg dry wt, respective ly; ANOVA, P<0.005). There was a strong correlation between medial cadmium content and pack-years of smoking (r=0.87, P<0.001). In aortic smooth muscl e cells cultured on fibrillar collagen, cadmium inhibited DNA synthesis and collagen synthesis and diminished cell numbers (IC50 2 mu mol/L, 6 mu mol/ L, and 6 mu mol/L, respectively), but higher concentrations of cadmium were required for upregulation of metallothionein (EC50 23 mu mol/L). The cadmi um content of the aorta increases in direct proportion to the pack-years of cigarettes smoked, with selective accumulation in the medial layer. Howeve r, the cadmium content of aneurysmal aortas was not higher than that of non dilated aortas for patients with matched smoking history. In smokers, the l evel of cadmium accumulation is probably sufficient to impair the viability of cultured smooth muscle cells. Similar mechanisms could underlie the dev elopment of degenerative aortic disease in smokers.