Deck 18: The Cardiovascular System As Conduit for a Dose Becoming a Dosage: Exposure and Toxicities

Question 1

How is methemoglobin not only a toxicity but a method for detecting other toxicants?

Answer 1

The formation of the Fe³⁺ methemoglobin is formed by oxidation of the Fe²⁺ hemoglobin. Methemoglobin does not carry oxygen (its toxicity) but can bind CN, which hemoglobin cannot. This is one way metHb is utilized to detect other toxicants.

Question 2

What effect does cadmium have on the vasculature?

Answer 2

Cadmium causes angiostatic chemotaxis inhibition and tube formation in vascular endothelium. This coupled to its hypertensive action through the kidney is problematic for the blood vessels.

Question 3

Why does cardiomyopathy develop readily from exposure of the heart to cancer chemotherapy anthracyclines, ethanol, or the antiviral AZT?

Answer 3

The heat is highly sensitive to oxidative agents. Its proximity to the lung and high content of mitochondria make this red organ dependent on oxygen (hypoxia generates ischemic injury).

Question 4

Why is the heart so sensitive to potassium and calcium concentrations in the blood? Why do these change the ECG?