WBR0739

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Physiology
Sub Category	SubCategory::Cardiology
Prompt	[[Prompt::A researcher is studying the role of a new drug for the prophylaxis against myocardial infarction. He explains that the medication acts on the arachidonic acid pathway and counteracts atherosclerosis by increasing compounds that inhibit platelet aggregation, a process proven to play a major role in the pathogenesis of coronary artery disease. According to the diagram below, the new drug most likely promotes which part of the pathway to achieve its therapeutic effect? ]]
Answer A	AnswerA::A
Answer A Explanation	AnswerAExp::LTB4 is a neutrophil chemotactic agent. It does not play a major role in reducing platelet aggregation.
Answer B	AnswerB::B
Answer B Explanation	AnswerBExp::LTC4 and LTD4 are pro-inflammatory agents that play a role in bronchoconstriction.
Answer C	AnswerC::C
Answer C Explanation	AnswerCExp::Prostacyclin is a major inhibitor of platelet aggregation.
Answer D	AnswerD::D
Answer D Explanation	AnswerDExp::Prostaglandins increase uterine tone. Prostaglandins may be administered to pregnant patients to induce labor. Prostaglandins also decrease vascular and bronchial tone.
Answer E	AnswerE::E
Answer E Explanation	AnswerEExp::Thromboxane A2 has an effect that opposes that of prostacyclin. It increases platelet aggregation and plays a role in worsening atherosclerosis.
Right Answer	RightAnswer::C
Explanation	[[Explanation::The medication described must have properties that reduce platelet aggregation to counteract the process of myocardial infarction. Prostacyclin (PGI2) is a potent inhibitor of platelet aggregation. Also, it plays a role in promoting vasodilation and bronchodilation, along with decreasing uterine tone. Since the drug increases compounds that inhibit platelet aggregation, the new compound must increase PGI2 levels, and thus promote inhibition of platelet aggregation. Educational Objective: Prostacyclin inhibits platelet aggregation. References: First Aid 2014 page 439]]
Approved	Approved::Yes
Keyword	WBRKeyword::Arachidonic, WBRKeyword::Acid, WBRKeyword::Pathway, WBRKeyword::Arachidonic acid pathway, WBRKeyword::Lipoxygenase, WBRKeyword::Cyclooxygenase, WBRKeyword::Platelet, WBRKeyword::Aggregation, WBRKeyword::Prostacyclin, WBRKeyword::PGI2, WBRKeyword::Thromboxane, WBRKeyword::Inhibitor, WBRKeyword::Inhibition, WBRKeyword::Therapeutic, WBRKeyword::Platelet aggregation, WBRKeyword::Therapeutic effect, WBRKeyword::Atherosclerosis, WBRKeyword::Myocardial, WBRKeyword::Infarction, WBRKeyword::MI
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::