Final answer:
Large IV doses of potassium penicillin G can cause lethal hyperkalemia by disrupting the electrochemical gradients in heart muscle cells, leading to cardiac arrhythmias and arrest, a mechanism also used in capital punishment and euthanasia.
Step-by-step explanation:
When large intravenous (IV) doses of potassium penicillin G are administered rapidly, a serious adverse effect that may occur is hyperkalemia, which is an abnormally high level of potassium in the blood.
Hyperkalemia can be lethal because potassium plays a critical role in maintaining the electrochemical gradients across cell membranes that are essential for the function of nerve and muscle cells, particularly heart muscle cells. Excess potassium can disrupt these gradients, leading to cardiac arrhythmias and cardiac arrest.
An injection of a potassium solution is lethal because it dissipates the electrochemical gradient in cardiac muscle cells, which prevents them from contracting effectively.
This can interrupt normal heart rhythms and lead to rapid heart failure. The conditions that involve such drastic changes, like capital punishment and euthanasia, are utilizing the fatal impact of disrupting heart function through the injection of high potassium solutions.