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Chapter 19: Nitric Oxide, Donors, & Inhibitors

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Which one of the following is not a nitric oxide donor but causes it to be synthesized and released from endogenous precursors, resulting in vasodilation?

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(A) Acetylcholine

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(B) Arginine

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(C) Isosorbide mononitrate

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(D) Nitroglycerin

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(E) Nitroprusside

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Nitroprusside and organic nitrites (eg, amyl nitrite) and nitrates (eg, nitroglycerin, isosorbide dinitrate, and isosorbide mononitrate) contain NO groups that can be released as NO. Arginine is the normal source of endogenous NO. Acetylcholine stimulates the synthesis of NO from arginine. The answer is A.

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A molecule that releases nitric oxide in the blood is

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(A) Citrulline

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(B) Histamine

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(C) Isoproterenol

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(D) Nitroglycerin

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(E) Nitroprusside

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Nitroprusside is the only molecule in this list that spontaneously releases NO in the bloodstream. The answer is E.

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The inducible isoform of nitric oxide synthase (iNOS, isoform 2) is found primarily in which of the following?

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(A) Cartilage

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(B) Eosinophils

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(C) Macrophages

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(D) Platelets

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(E) Vascular endothelial cells

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The inducible form of NOS is associated with inflammation, and the enzyme is found in highest concentration in macrophages, cells that are particularly involved in inflammation. The answer is C.

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The primary endogenous substrate for the enzyme nitric oxide synthase (NOS) is

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(A) Acetylcholine

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(B) Angiotensinogen

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(C) Arginine

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(D) Citrulline

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(E) Heme

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Arginine is the substrate and citrulline and NO are the products of NOS. The answer is C.

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Which of the following is a recognized effect of nitric oxide (NO)?

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(A) Arrhythmia

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(B) Bronchoconstriction

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(C) Constipation

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(D) Inhibition of acute graft rejection

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(E) Pulmonary vasodilation

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NO does not cause ...

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