**Question:** Which of the following is not a clinical sign of atropine intoxication?

A. Tachycardia
B. Hypertension
C. Dry mouth
D. Increased bronchial secretions

**Correct Answer: B. Hypertension**

**Core Concept:** Atropine is a potent anticholinergic drug that competes with scopolamine for binding to muscarinic receptors. Atropine intoxication leads to blockade of muscarinic receptors, causing various clinical signs and symptoms.

**Why the Correct Answer is Right:** Hypertension is not a typical clinical sign of atropine intoxication, as it is expected to cause peripheral vascular dilatation, leading to hypotension due to decreased vasoconstriction and increased blood volume. Atropine's primary effect is to antagonize the action of acetylcholine at muscarinic receptors, which are involved in regulating blood pressure.

**Why Each Wrong Option is Incorrect:**

**A. Tachycardia:** This is a correct answer because tachycardia (increased heart rate) is a common manifestation of atropine intoxication, as it competes with acetylcholine for binding to muscarinic receptors. Blockade of these receptors leads to increased cardiac stimulation and increased heart rate.

**C. Dry mouth:** Similar to tachycardia, dry mouth (xerostomia) is a correct answer due to the blockade of muscarinic receptors in the salivary glands, which reduces saliva production.

**D. Increased bronchial secretions:** Increased bronchial secretions (bronchorrhoea) are also correct, as atropine blocks muscarinic receptors in the bronchial secretory glands, leading to increased secretion.

**Clinical Pearl:** Clinical signs and symptoms of atropine intoxication are predominantly related to muscarinic receptor blockade, which affects cardiac, respiratory, and gastrointestinal systems.

**Explanation of Clinical Signs:**

1. Tachycardia: Atropine blocks the action of acetylcholine, resulting in increased cardiac stimulation and increased heart rate.
2. Dry mouth: Muscarinic receptors in salivary glands are blocked by atropine, leading to reduced saliva production and dry mouth.
3. Increased bronchial secretions: Blockade of muscarinic receptors in bronchial secretory glands leads to increased bronchial secretion and bronchorrhoea.

**Core Principle:** Understanding the pharmacology of atropine and its effects on muscarinic receptors will help you recognize the clinical signs of atropine intoxication in clinical practice.