True about Prostacyclin

Correct Answer: D

Rationale: Step-by-step rationale: 1. Prostacyclin is a vasodilator, so it causes vasodilation, not vasoconstriction. 2. Prostacyclin inhibits platelet aggregation, so it does not promote it. 3. Prostacyclin helps decrease blood pressure by promoting vasodilation. 4. Prostacyclin is synthesized from vascular endothelium, making choice D the correct answer. Summary: A: Incorrect - Prostacyclin causes vasodilation, not vasoconstriction. B: Incorrect - Prostacyclin inhibits platelet aggregation, not promotes it. C: Incorrect - Prostacyclin helps decrease blood pressure, not increase it. D: Correct - Prostacyclin is synthesized from vascular endothelium.

Correct Answer: D

Rationale: Platelet aggregation is a complex process involving various mediators. Prostaglandins and thromboxane are both derived from arachidonic acid and play crucial roles. Thromboxane promotes platelet aggregation by stimulating vasoconstriction and platelet activation. Prostaglandins also contribute to platelet aggregation by enhancing thromboxane synthesis and promoting platelet adhesion. Prostacyclin, on the other hand, inhibits platelet aggregation by inducing vasodilation and inhibiting platelet activation. Therefore, the correct answer is D, as both prostaglandins and thromboxane promote platelet aggregation. Choices A, B, and C are incorrect as they do not capture the dual role of prostaglandins and thromboxane in platelet aggregation.

Correct Answer: D

Rationale: Correct Answer: D - Vecuronium Rationale: Vecuronium is a non-depolarizing neuromuscular blocking agent that blocks the action of acetylcholine at the neuromuscular junction, preventing muscle contraction. It does not directly cause muscle contractions or twitching. Summary: A: Acetylcholine - Stimulates muscle contraction by binding to receptors at the neuromuscular junction. B: Strychnine - Enhances spinal reflexes leading to muscle twitches and spasms. C: Succinylcholine - Acts as a depolarizing neuromuscular blocker, leading to muscle contractions.

Correct Answer: B

Rationale: The correct answer is B: MAO inhibitors. Phenelzine and tranylcypromine are both monoamine oxidase inhibitors (MAOIs). MAOIs work by blocking the enzyme monoamine oxidase, which increases the levels of neurotransmitters such as serotonin, norepinephrine, and dopamine in the brain. This leads to an improvement in mood and alleviation of depressive symptoms. Tricyclic antidepressants (choice A) work by blocking the reuptake of neurotransmitters, 5-HT uptake inhibitors (choice C) specifically target serotonin reuptake, and atypical antidepressants (choice D) have various mechanisms of action different from MAOIs. Therefore, the correct choice is B as phenelzine and tranylcypromine are classified as MAO inhibitors.

Correct Answer: D

Rationale: The correct answer is D: Promotes GABA release. Gabapentin increases the release of GABA, an inhibitory neurotransmitter in the brain, which helps to reduce abnormal electrical activity and alleviate pain. This mechanism of action is different from choices A, B, and C, as Gabapentin does not bind to GABAA or GABAB receptors nor inhibit GABA destruction. It is important to understand the specific pharmacological actions of Gabapentin to grasp its therapeutic effects accurately.