In vitro toxicity of mercury, cadmium, and arsenic to platelet aggregation: influence of adenylate cyclase and phosphodiesterase activity.

In vitro effect of mercury (Hg2+), cadmium (Cd2+), and arsenic (As3+) on adenylate cyclase (AC) and phosphodiesterase (PDE) activity in relation to platelet aggregation (PA) was studied in rats. Cd(2+) significantly elevated cAMP (p < 0.005) in a dose-dependent (5, 10 and 20 pmoles) manner while Hg(2+) and As(3+) significantly reduced the cAMP level (p < 0.01 and p < 0.005, respectively). Our studies further reveal that Hg21 and As(3+) inhibit AC and stimulate PDE activity with a concomitant increase in the rate of PA. On the other hand, Cd(2+) stimulates AC and inhibits PDE activity with a decrease in the rate of PA. The present investigation suggests that cellular cAMP is a regulatory molecule in the event of PA and the disruption of its homeostasis is directly correlated to xenobiotic effects on PA. It is concluded that other than divalent heavy metal cations, As(3+) appears to be one of the most toxic xenobiotics to platelet function.