Pharmacology of Ion Channels and Enzymes

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Questions and Answers

What is one way ion channels can be activated?

By direct interaction with lipids
By affecting protein synthesis within the cell
By irreversible inhibition of enzymes
By altering the level of expression of ion channels on the cell surface (correct)

Which type of drug action is exemplified by ACE inhibitors?

Competitive inhibitor (correct)
Prodrug activation
False substrate
Irreversible, non-competitive inhibitor

What characterizes active transporters?

They rely on concentration gradients for transport
They can only transport a single type of ion
They are ATP dependent (correct)
They do not require energy to transport molecules

What is a key feature of false substrates like fluorouracil?

<p>They act similarly to the normal substrate of the enzyme (C)</p> Signup and view all the answers

How does the transport of organic molecules typically occur with inactive transport?

<p>Coupled with the transport of ions in the same direction (B)</p> Signup and view all the answers

Flashcards

Indirect Ion Channel Activation

Ion channels can be activated indirectly through a G protein and other intermediaries. This involves a chain of events where a signal binds to a receptor, activating the G protein, which then triggers a series of downstream events leading to the opening of the ion channel.

Altering Ion Channel Expression

Some drugs, like gabapentin, can decrease the number of ion channels on the cell surface by interfering with their insertion into the plasma membrane. This impacts the overall number of channels available for signaling.

Competitive Enzyme Inhibition

ACE inhibitors (ACEIs) compete with angiotensin I for binding to the active site of the angiotensin-converting enzyme (ACE), blocking its function in converting angiotensin I to angiotensin II. This decreases blood pressure by preventing vasoconstriction.

Irreversible Enzyme Inhibition

Aspirin irreversibly inhibits cyclooxygenase (COX) enzymes by acetylating a key amino acid in the active site. This permanently disables the enzyme's ability to synthesize prostaglandins, which are involved in inflammation and pain.

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Prodrug Activation

A prodrug is an inactive drug that must be converted to its active form by enzymes in the body. This is a way to improve drug delivery or stability.

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Study Notes

Ion Channels Activation

Ion channels can be activated indirectly through G proteins and other intermediaries.
The expression level of ion channels on the cell surface can be altered, impacting their function.
Gabapentin is an example of a drug that reduces the insertion of neuronal calcium channels into the plasma membrane.

Enzymes

Drugs can affect enzyme function in several ways:
- Competitive inhibition (e.g., ACEIs)
- Irreversible/non-competitive inhibition (e.g., Aspirin)
- Using false substrates (e.g., fluorouracil)
Enzymes also play a role in drug actions:
- Drug activation (prodrug activation)
- Drug metabolism

Transporters

Active transport relies on ATP and specific carriers (e.g., ABC transporters).
In passive transport, solute carriers move molecules across membranes.
Coupled transport, or co-transport, occurs when the movement of one molecule is dependent on the movement of another, in the same or opposite direction (e.g., symport, antiport).