The effects of low level chronic lead (7439921) exposure on myocardial protein expression were studied in rabbits. Male Dutch- Belted-rabbits were sham exposed or injected subcutaneously with 260, 360, or 1,300 micrograms (microg) per kilogram lead as lead- acetate (301042) for 5 weeks (wk) to achieve target blood lead concentrations of 20, 40, or 80microg per deciliter (microg/dl). After this, the animals were placed on 'maintenance doses', that were adjusted weekly when necessary, for the next 10wk to maintain blood lead concentrations at 20, 40, or 80microg/dl. The animals were killed after the 10wk period and weighed. The hearts were removed and weighed. The hearts were then homogenized. The homogenates were analyzed for lead, after which they were analyzed by two dimensional electrophoresis to examine changes in the distribution of myocardial proteins. Lead exposure did not significantly affect body weight or absolute and relative heart weights. The cardiac lead concentrations in rabbits with target blood lead concentrations of 20, 40, and 80microg/dl averaged 69, 102, and 105 nanograms per gram (ng/g), respectively. The mean cardiac lead concentration in control animals was 58ng/g. A total of 808 individual myocardial proteins were resolved by the electrophoretic technique. Of these, 162 could be identified by matching to a master pattern. No changes in the protein distribution pattern attributable to lead exposure were observed. The authors conclude that chronic low level lead exposure does not cause detectable effects on major myocardial proteins in rabbits.