From ancient times, humans have used<unk> -containing plants and their crude extracts as arrow coatings, homicidal or suicidal aids, rat poisons, heart tonics, diuretics and emetics, primarily due to the toxic nature of these compounds. Thus, though<unk> s have been used for their medicinal function, their toxicity must also be recognized. For example, in 2008 US poison centers reported 2,632 cases of digoxin toxicity, and 17 cases of digoxin-related deaths. Because<unk> s affect the cardiovascular, neurologic, and gastrointestinal systems, these three systems can be used to determine the effects of toxicity. The effect of these compounds on the cardiovascular system presents a reason for concern, as they can directly affect the function of the heart through their inotropic and chronotropic effects. In terms of inotropic activity, excessive<unk>  dosage results in<unk>  contractions with greater force, as further calcium is released from the SR of<unk>  muscle cells. Toxicity also results in changes to heart chronotropic activity, resulting in multiple kinds of dysrhythmia and potentially fatal ventricular tachycardia. These dysrhythmias are an effect of an influx of sodium and decrease of resting membrane potential threshold in<unk>  muscle cells. When taken beyond a narrow dosage range specific to each particular<unk> , these compounds can rapidly become dangerous. In sum, they interfere with fundamental processes that regulate membrane potential. They are toxic to the heart, the brain, and the gut at doses that are not difficult to reach. In the heart, the most common negative effect is Premature ventricular contraction.
Cardiac glycoside
Phytosteroid
Insulin analog
Glucocorticoid
Steroid ester
Eoxin
Clofibride
Xenohormone