The anesthetic effect of the agents of short and intermediate duration of action can not be prolonged by adding:

Correct Answer: C

Rationale: Step-by-step rationale: 1. The anesthetic effect of short and intermediate duration agents is primarily influenced by their metabolism and distribution in the body. 2. Dopamine is not commonly used to prolong anesthesia as it primarily acts as a neurotransmitter and vasopressor. 3. Epinephrine, norepinephrine, and phenylephrine are commonly used to prolong anesthesia due to their vasoconstrictive properties. 4. Therefore, the correct answer is C (Dopamine) as it does not have the same vasoconstrictive effects as the other choices.

Correct Answer: C

Rationale: Step-by-step rationale: 1. Succinylcholine causes transient muscle fasciculations due to its depolarizing mechanism of action. 2. It binds to nicotinic acetylcholine receptors, causing initial muscle twitching. 3. This fasciculation phase is a distinct feature of succinylcholine. 4. Mivacurium, Pancuronium, and Tubocurarine are non-depolarizing blockers, so they do not cause initial muscle fasciculations. Summary: A, B, and D are incorrect because they are non-depolarizing blockers and do not induce muscle fasciculations like succinylcholine.

Correct Answer: D

Rationale: Isoproterenol is a nonselective beta receptor agonist. It activates both beta1 and beta2 adrenergic receptors. This is because it has a higher affinity for beta receptors compared to alpha receptors, making it nonselective. Therefore, option D is correct. Option A is incorrect because isoproterenol does not significantly activate alpha receptors. Option B is incorrect as it is not beta1-selective. Option C is incorrect as isoproterenol activates both beta1 and beta2 receptors.

Correct Answer: B

Rationale: The correct answer is B because propranolol does not reduce blood flow to the brain. Propranolol is a non-selective beta-blocker that decreases cardiac work and oxygen demand (choice A), inhibits renin secretion (choice C), and increases the atrioventricular nodal refractory period (choice D). By blocking beta receptors in the heart and blood vessels, propranolol reduces heart rate, contractility, and blood pressure, leading to decreased oxygen demand. Inhibiting renin secretion helps lower blood pressure. Increasing the atrioventricular nodal refractory period can slow down the conduction of electrical impulses in the heart, helping to control heart rhythm. Therefore, choices A, C, and D are all accurate effects of propranolol on the cardiovascular system.

Correct Answer: C

Rationale: The correct answer is C: Flurazepam. Flurazepam is a benzodiazepine hypnotic drug that causes the least suppression of REM sleep compared to the other options. Benzodiazepines like flurazepam enhance the quality of sleep without significantly disrupting REM sleep. Flumazenil (A) is a benzodiazepine receptor antagonist, not a hypnotic drug. Phenobarbital (B) and Secobarbital (D) are barbiturates that are known to suppress REM sleep significantly, unlike flurazepam. In summary, flurazepam is the best choice for a hypnotic drug that minimally affects REM sleep compared to the other options provided.