A method for enriching the cadmium content of cigarette smoke and effect of exposure to this smoke on coronary vascular reactivity in the rat

To study the effect of smoke-borne cadmium on the cardiovascular system, a method was developed to vary the cadmium content in the smoke of Kentucky 2R1 reference cigarettes. 2R1 filler tobacco was sprayed with aqueous solutions of CdSO₄; cigarettes were prepared from this tobacco and smoked through Cambridge filters. These treatments increased the cadmium content of the cigarette smoke from 0.23 ± 0.01 μg Cd 2R1 cigarette to 0.317 ± 0.029, 2.38 ± 0.092, and 4.9 ± 0.1 μg Cd/cigarette for 500 μm, and 50 mm CdSO₄, respectively. Male Sprague-Dawley rats were exposed for 5 or 23 weeks to smoke from 2R1 reference cigarettes and cigarettes prepared from 2R1 tobacco that was treated with 500 μm CdSO₄. Following 5 weeks of smoke exposure, neither kidney cadmium amount nor coronary vascular reactivity to angiotensin was altered in either smoke-exposed group compared to cage controls or sham-smoked animals. After 23 weeks of exposure, cadmium amounts in kidneys from animals exposed to cadmium-enriched smoke were significantly greater than quantities observed in any other group. Exposure to either type of cigarette smoke increased coronary vascular reactivity above either control group. Exposure to cadmium-enriched cigarette smoke increased coronary vascular reactivity to angiotensin above the amount observed following exposure to 2R1 cigarette smoke. This finding indicates that smoke-borne cadmium may mediate the observed increases in coronary vascular reactivity following exposure to cigarette smoke.