Lower esophageal sphincter pressure is increased by all of the following substances, EXCEPT:
**Core Concept**
The lower esophageal sphincter (LES) plays a crucial role in preventing gastroesophageal reflux by maintaining a pressure barrier between the esophagus and stomach. Various substances can influence LES pressure through different mechanisms.
**Why the Correct Answer is Right**
To answer this question, we need the actual options. However, generally, substances that increase LES pressure do so by enhancing cholinergic activity or directly stimulating the smooth muscle of the LES.
**Why Each Wrong Option is Incorrect**
**Option A:** Would be incorrect if it were a substance like gastrin or motilin, which are known to increase LES pressure.
**Option B:** Might be incorrect if it involved a cholinergic agonist.
**Option C:** Could be incorrect if it were a substance that enhances gastrointestinal motility and thus increases LES pressure.
**Why Each Wrong Option is Incorrect (Continued)**
Without actual options, we can't proceed accurately. Normally, we'd discuss how each option affects LES pressure, focusing on the incorrect ones.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that the lower esophageal sphincter's pressure is crucial for preventing reflux, and its dysfunction can lead to conditions like gastroesophageal reflux disease (GERD).
**Correct Answer Line**
**Correct Answer: D.**