The increase of second messengers’ (cAMP, cGMP, Ca2+ etc.) concentration leads to:

Correct Answer: B

Rationale: The increase of second messengers concentration, such as cAMP, cGMP, and Ca2+, leads to the activation of protein kinases and subsequent protein phosphorylation. This is because second messengers act as signaling molecules that trigger a cascade of intracellular events, including the activation of protein kinases. Protein kinases then phosphorylate target proteins, modulating their activity and initiating various cellular responses. Therefore, choice B is correct as it accurately describes the downstream effect of increased second messengers' concentration. Choices A, C, and D are incorrect because they do not align with the established signaling pathway involving second messengers and protein kinases.

Correct Answer: D

Rationale: The correct answer is D: Weakness of all skeletal muscles. Excessive stimulation of muscarinic receptors would not lead to weakness of skeletal muscles because muscarinic receptors are mainly found in smooth muscles and glands, not skeletal muscles. A: Abdominal cramps, diarrhea, B: Increased salivation, excessive bronchial secretion, and C: Miosis, bradycardia are all symptoms of excessive muscarinic receptor stimulation as these receptors are involved in various functions in the body such as gastrointestinal motility, salivation, bronchial secretions, pupil constriction, and heart rate regulation.

Correct Answer: C

Rationale: Rationale: Mivacurium is the correct answer as it is a nondepolarizing neuromuscular blocking agent with a short duration of action due to its rapid metabolism by plasma esterases. Succinylcholine (A) is a depolarizing agent, Tubocurarine (B) and Pancuronium (D) are nondepolarizing agents with longer durations of action compared to Mivacurium.

Correct Answer: C

Rationale: Rationale: 1. Phenylephrine is a relatively pure alpha agonist, constricts blood vessels, and increases blood pressure. 2. It is an effective mydriatic due to its alpha-adrenergic effects. 3. Phenylephrine is a decongestant by constricting nasal blood vessels. 4. Epinephrine and norepinephrine are non-selective agonists with more diverse effects. 5. Ephedrine acts on both alpha and beta receptors, making it less specific for raising blood pressure.

Correct Answer: C

Rationale: The correct answer is C because beta-blocking agents do not induce depression or deplete stores of catecholamines. Here's the rationale: 1. Option A is correct as beta blockers occupy beta receptors, competitively reducing receptor occupancy by catecholamines. 2. Option B is incorrect because beta blockers can cause hypotension as one of their side effects, especially in individuals with normal blood pressure. 3. Option D is correct as beta blockers can cause blockade in the atrioventricular node, leading to decreased heart rate and conduction. In summary, beta blockers do not induce depression or deplete catecholamine stores, making option C the correct answer.