All of the following are cardiovascular actions of noradrenaline EXCEPT:

Correct Answer: D

Rationale: Noradrenaline acts on alpha receptors in the cardiovascular system, leading to increased systolic and diastolic blood pressure. It also causes reflex bradycardia by activating baroreceptors. However, noradrenaline does not directly constrict coronary blood vessels, as it primarily acts on alpha receptors and not on coronary vessels. This lack of direct effect on coronary blood vessels is why option D is the correct answer.

Correct Answer: D

Rationale: The correct answer is D: Alpha 1 receptor stimulation releases IP3 and DAG. When alpha 1 receptors are stimulated by sympathomimetics, they activate G-proteins which then stimulate phospholipase C. Phospholipase C cleaves phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol trisphosphate (IP3) and diacylglycerol (DAG). IP3 triggers the release of calcium from intracellular stores, leading to smooth muscle contraction, while DAG activates protein kinase C to initiate various cellular responses. Choices A, B, and C are incorrect because beta receptor stimulation increases cAMP, alpha 2 receptor stimulation inhibits adenyl cyclase leading to decreased cAMP levels, and alpha 2 receptor stimulation does not increase cAMP.

Correct Answer: D

Rationale: The correct answer is D because ephedrine and amphetamine are not catecholamines. A is correct as catecholamines contain a catechol nucleus. B is true as they act directly on receptors. C is also true since catecholamines have a short duration of action. Therefore, D is the incorrect statement as ephedrine and amphetamine do not fall under the category of catecholamines due to their chemical structure and mode of action.

Correct Answer: B

Rationale: Propranolol is a non-selective beta-blocker that can cause bronchoconstriction, making it contraindicated in bronchial asthma. It can worsen asthma symptoms by blocking beta-2 receptors in the lungs. Angina pectoris, hypertension, and arrhythmia are conditions where propranolol is commonly used due to its beta-blocking effects on the heart and blood vessels.

Correct Answer: C

Rationale: The correct answer is C: Amitriptyline. Amitriptyline is a tricyclic antidepressant known for its anticholinergic properties, causing dry mouth, constipation, blurred vision, and urinary retention. Anticholinergic effects result from blocking the action of acetylcholine in the parasympathetic nervous system. Codeine (A) is an opioid, Ciprofloxacin (B) is an antibiotic, and Propranolol (D) is a beta-blocker, none of which are expected to cause significant anticholinergic effects.