Question

A susceptible population is treated with ivermectin to prevent onchocerciasis (river blindness). The permeability of which ion is increased in the parasite by this treatment? (A) calcium (B) magnesium (C) potassium (D) sodium (E) chloride

Short answer

Ivermectin increases the permeability of chloride ions (option E).

Step-by-step solution

Identify the Drug's Mechanism

Ivermectin works by increasing the permeability of certain ions in parasites, leading to paralysis and death of the parasite.

Consider the Effect of Increased Ionic Permeability

Increased ionic permeability disrupts the normal functioning of the parasite's nervous system, aiding in the prevention of diseases like onchocerciasis.

Match Ion Permeability with Known Effects

Ivermectin is known to increase the permeability of chloride ions in the parasitic membrane. This influx of chloride ions hyperpolarizes the cell membrane, leading to paralysis.

Determine the Correct Ion

Cross-reference this knowledge with the given options. Ivermectin is specifically associated with increased chloride ion permeability.

Key concepts

Ionic Permeability

Ionic permeability refers to the ability of ions to pass through cell membranes or channels. In neurophysiology, this is a crucial concept because ions such as sodium, potassium, calcium, and chloride play critical roles in generating nerve impulses.

When we refer to increased ionic permeability, it means that a particular ion is able to move more freely across the cell membrane. This can lead to dramatic effects on a cell's electrical activity. In the case of parasites like those causing onchocerciasis, increased permeability often results in disruption of normal cellular functions.

Ivermectin, a medication used to treat infections caused by parasites, specifically targets and increases the permeability of chloride ions in the parasites. This disrupts the normal ion balance, leading to paralysis and subsequent death of the parasites, effectively treating diseases such as onchocerciasis.

Chloride Ions in Pharmacology

Chloride ions play a vital role in pharmacology due to their involvement in maintaining cell membrane potential and cell signaling. They are one of the critical agents involved in maintaining the electrical potential across cell membranes.

In pharmacological treatments like the use of ivermectin, chloride ions become the focus because ivermectin enhances their permeability in parasitic cells. By increasing chloride ion entry into cells, the medication causes hyperpolarization. This effect makes the interior of the cell more negative compared to the outside.
- Hyperpolarization inhibits normal neuronal activity. - For parasites, this means they become paralyzed and die, as they can no longer maintain essential functions such as movement and reproduction.
Thus, pharmaceuticals that manipulate chloride ion permeability can effectively disrupt parasitic life cycles, providing a means to combat infections like onchocerciasis.

Onchocerciasis Treatment

Onchocerciasis, commonly known as river blindness, is caused by a parasitic worm transmitted through the bite of blackflies. This disease primarily affects the skin and eyes, leading to severe itching and potential blindness if left untreated.

Ivermectin is the primary treatment for onchocerciasis. It works by targeting the parasitic worms, interfering with their nervous systems through increased chloride ion permeability, which leads to paralysis and death.
- Regular administration of ivermectin helps to significantly reduce the microfilarial burden in infected individuals. - This treatment is effective in controlling the symptoms and reducing transmission, although it does not kill the adult parasites.
The widespread use and donation of ivermectin in affected regions have made it a cornerstone in the fight against this disease, improving the quality of life for those in endemic areas.

Parasite Neurophysiology

Parasite neurophysiology refers to the study of how parasitic organisms' nervous systems operate and how they can be disrupted. Understanding this is key for developing treatments that target parasites effectively.

Parasites such as those causing onchocerciasis rely on their nervous systems for mobility, feeding, and reproduction. Disruption of these systems can render the parasites non-functional or dead.
- The nervous system of parasites operates similarly to other organisms, relying on the movement of ions across membranes to send signals. - Medications like ivermectin exploit this by increasing the permeability of chloride ions, thereby hyperpolarizing the cell and cutting off nerve signal transmission.
By focusing on the neurophysiological pathways of parasites, researchers and healthcare providers can develop effective treatments that specifically disrupt these neural functions, thereby leading to the paralysis and elimination of the parasitic threat.