**Core Concept**
Ion channel receptors are a type of ligand-gated ion channel that allows ions to flow through the cell membrane in response to the binding of a specific ligand. These receptors play a crucial role in various physiological processes, including neurotransmission and muscle contraction. Examples of drugs that act through ion channel receptors include benzodiazepines, which enhance GABAergic activity by binding to GABA_A receptors.

**Why the Correct Answer is Right**
Drugs that do not act through ion channel receptors typically interact with other types of receptors, such as G protein-coupled receptors (GPCRs) or enzyme-linked receptors. These receptors trigger a variety of downstream signaling pathways that ultimately lead to a response in the cell. For example, beta-blockers, such as propranolol, act through GPCRs to inhibit the effects of catecholamines on the heart.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is a type of drug that does act through ion channel receptors, specifically by enhancing GABAergic activity.
**Option B:** This option is incorrect because it is a type of drug that acts through GPCRs, specifically by inhibiting the effects of catecholamines on the heart.
**Option C:** This option is incorrect because it is a type of drug that acts through enzyme-linked receptors, specifically by inhibiting the conversion of angiotensin I to angiotensin II.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that not all drugs act through ion channel receptors, and understanding the different types of receptors and their mechanisms of action is crucial for effective pharmacological management of various diseases.

**Correct Answer: B. Propranolol**