Atropine causes each of the following EXCEPT which?

Atropine causes each of the following EXCEPT which?

• A. Decreased gastric acid secretion
• B. Inhibition of salivary secretion
• C. Tachycardia
• D. Increased lower esophageal sphincter tone

Answer: (D)

Atropine blocks muscarinic receptors, dampening parasympathetic actions. Because acetylcholine via muscarinic receptors normally stimulates secretions and slows the heart, blocking these receptors with atropine leads to less gastric acid secretion, reduced salivary secretion, and an increased heart rate due to loss of vagal braking. For the lower esophageal sphincter, acetylcholine tends to increase its tone by promoting contraction. Blocking this effect with atropine reduces, not increases, LES tone. Therefore the statement about increased LES tone is not an effect of atropine.

Atropine blocks muscarinic receptors, dampening parasympathetic actions. Because acetylcholine via muscarinic receptors normally stimulates secretions and slows the heart, blocking these receptors with atropine leads to less gastric acid secretion, reduced salivary secretion, and an increased heart rate due to loss of vagal braking.

For the lower esophageal sphincter, acetylcholine tends to increase its tone by promoting contraction. Blocking this effect with atropine reduces, not increases, LES tone. Therefore the statement about increased LES tone is not an effect of atropine.