All of the following drugs act by blocking calcium channel except
**Core Concept**
The question is testing the student's knowledge of calcium channel blockers, a class of medications that inhibit the influx of calcium ions into cardiac and smooth muscle cells, leading to vasodilation and a decrease in cardiac contractility.
**Why the Correct Answer is Right**
Calcium channel blockers work by inhibiting the L-type calcium channels, which are responsible for the influx of calcium ions during depolarization. This leads to a decrease in the contractility of the heart and blood vessels, resulting in a decrease in blood pressure and cardiac workload. Examples of calcium channel blockers include nifedipine, verapamil, and diltiazem.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so we will move on to the next one.
* **Option B:** This option is not provided, so we will move on to the next one.
* **Option C:** This option is not provided, so we will move on to the next one.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that calcium channel blockers can have different effects on the heart and blood vessels depending on their specific mechanism of action. Verapamil, for example, has a negative inotropic effect (decreases contractility) and is often used to treat hypertension and angina, while nifedipine has a vasodilatory effect and is often used to treat Raynaud's disease.
**Correct Answer:** D.