The predominant isozyme of LDH in Lung is:
**Core Concept**
The question is testing the student's knowledge of lactate dehydrogenase (LDH) isozymes and their tissue distribution. LDH is an enzyme involved in the conversion of lactate to pyruvate, and it exists in five different isozymes, each with a different tissue distribution.
**Why the Correct Answer is Right**
The predominant isozyme of LDH in lung tissue is LDH-2. This is because LDH-2 is the isozyme that is most highly expressed in lung tissue, where it plays a crucial role in the metabolism of lung cells. The correct answer is LDH-2 because it is the isozyme that is most closely associated with lung tissue.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because LDH-1 is the isozyme that is predominantly found in cardiac muscle, not lung tissue.
* **Option B:** This option is incorrect because LDH-3 is the isozyme that is predominantly found in the kidneys, not lung tissue.
* **Option C:** This option is incorrect because LDH-4 is the isozyme that is predominantly found in the liver, not lung tissue.
* **Option D:** This option is incorrect because LDH-5 is the isozyme that is predominantly found in the skeletal muscle, not lung tissue.
**Clinical Pearl / High-Yield Fact**
It's worth noting that LDH isozymes can be used as markers for certain types of cancer, including lung cancer. Elevated levels of LDH-2 in lung tissue can be indicative of lung cancer, making it an important enzyme to test in patients with suspected lung cancer.
**Correct Answer:** LDH-2.