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Questions and Answers

Match each to its description

nitric oxide (NO) = gaseous signaling molecule nitrous oxide (N2O) = a gas anesthetic nitrogen dioxide (NO2) = a toxic pulmonary gas

Match each isoform to its category

= neuronal NOS = nNOS or NOS-1 macrophage inducible NOS = iNOS or NOS-2 endothelial NOS = eNOS or NOS-3

Which of the following produces nitric oxide when nitric oxide synthase is added?

L-arginine (correct)

L-citrulline

D-arginine

L-lysine

Which of the following drugs is used specifically to treat angina by being converted into nitric oxide?

Nitroglycerin Signup and view all the answers

What is a potential consequence of excessive nitric oxide production during septic shock?

Hypotensive crisis Signup and view all the answers

What is the primary role of nitric oxide in the central nervous system (CNS)?

Enhance neurotransmitter release Signup and view all the answers

Which of the following is known to be an inhibitor of nitric oxide synthesis?

Nitric oxide synthase inhibitors Signup and view all the answers

Which drug is classified as a nitrite and is known for its abuse as an inhalant?

Amyl nitrite Signup and view all the answers

How does nitric oxide primarily affect blood pressure regulation?

By promoting vasodilation Signup and view all the answers

What is the effect of nitric oxide in relation to platelet aggregation?

Inhibits platelet aggregation Signup and view all the answers

Which condition can lead to the induction of inducible nitric oxide synthase (iNOS) and subsequently produce high levels of nitric oxide?

Septic shock Signup and view all the answers

What is the significance of nitric oxide's (NO) unpaired electron in its structure?

It contributes to the reactivity of NO, allowing it to interact with various cellular components. Signup and view all the answers

Which function is primarily associated with endothelial nitric oxide synthase (eNOS)?

Regulation of vascular relaxation through cGMP production. Signup and view all the answers

How does nitric oxide (NO) interact with metalloproteins?

By interacting with the metal, influencing protein activity. Signup and view all the answers

What role does inducible nitric oxide synthase (iNOS) play in the body?

It is activated in response to injury or inflammation. Signup and view all the answers

In what way does the formation of nitrosothiols by nitric oxide affect cellular functions?

It leads to the inactivation of certain proteins. Signup and view all the answers

What evidence contributed to the discovery of nitric oxide (NO) as a significant biological signaling molecule?

The generation of cGMP upon NO interaction with guanyl cyclase. Signup and view all the answers

Which condition is characterized by increased nitric oxide (NO) synthesis leading to potential biological complications?

Increased levels of peroxynitrite in inflammation. Signup and view all the answers

What is the primary difference between nitric oxide (NO) and nitrous oxide (N2O)?

NO is a gaseous signaling molecule, whereas N2O is primarily used as an anesthetic. Signup and view all the answers

What is formed when NO binds to sulfa (-SH)?

Nitrogen Dioxide Signup and view all the answers

What can NO interaction with the metalloproteins in guanylate cyclase lead to?

Vascular relaxation Signup and view all the answers

What can occur when NO binds to the sulfa group in vascular glutathione? (Select all that apply)

Protein inactivation Signup and view all the answers

Which group of people have reduced glutathione levels and higher rates of cardiac complications?

Diabetics Signup and view all the answers

NO can lead to peroxynitrite levels which interact with which of the following amino acids?

Tyrosine Signup and view all the answers

Match each drug to its effects/ usage

Nitroglycerin (Nitrate) = converted into NO by enzymes in the cell walls, venous smooth muscle relaxation. Used to treat angina. Isosorbide dinitrate = generates NO after taken PO or used as a spray topical. Used by podiatrists to promote better blood flow in legs. amyl nitrite = Is converted into NO, used as an inhalant, abused as “poppers”. Sodium Nitroprusside = Used to treat severe hypertension. Signup and view all the answers

Which of the following fits the description below:

Reduces pulmonary artery pressure and improves perfusion of ventilated areas of the lung.

Gas drug used to treat pulmonary hypertension?

NO Gas Signup and view all the answers

Match each disease to NO's effect

= Vascular Effects = major vasodilator and controller of blood pressure (BP); inhibits platelet aggregation; acts as an antioxidant, protecting from free radical active compounds Septic Shock = Endotoxins produced by bacteria induce iNOS to produce high levels of NO;excess production of NO can lead to extensive vasodilation, lowered BP up to hypotensive crisis and death Infection & Inflammation = an induce iNOS in white cells and other cells. This can lead to a stimulation of the beneficial immune response, but, excess NO can lead to exacerbation of cell injury Signup and view all the answers

In which system does NO act as a presynaptic neurotransmitter that results in enhancing neurotransmitter release?

CNS Signup and view all the answers

In which system is nitric oxide (NO) released by nonadrenergic and noncholinergic receptors to promote vasodilation?

PNS Signup and view all the answers

Study Notes

Nitric Oxide (NO)

NO is a gaseous signaling molecule, a significant discovery in medicine, and a gas anesthetic.
NO is synthesized in various cells and triggers intracellular signaling pathways.
NO production is observed in macrophages treated with bacterial endotoxins, resulting in nitrate and nitrite metabolites.
NO-induced vasorelaxation is noted in endothelial cells.
NO is the main component of endothelium-derived relaxing factor (EDRF)
There are three isoforms of nitric oxide synthase (NOS) that produce NO in tissues.
- Neuronal NOS (nNOS or NOS-1)
- Macrophage inducible NOS (iNOS or NOS-2)
- Endothelial NOS (eNOS or NOS-3)
L-arginine is the precursor for NO synthesis via NOS.

Targets of NO

Metalloproteins: NO binds to metals in proteins and leads to interaction with iron in proteins like hemoglobin and guanylyl cyclase.
Thiols: NO reacts with sulfa groups (-SH) of proteins, forming nitrosothiols, influencing protein activity.
Tyrosine: NO can lead to peroxynitrite formation, altering protein activity by nitrating tyrosine residues.

NO Production and Regulation

Organic nitrates, like nitroglycerin and isosorbide dinitrate, are converted into NO in the body, leading to smooth muscle relaxation and used to treat angina.
Organic nitrites, like amyl nitrite, are converted to NO and used as inhalants.
Sodium nitroprusside is a drug used to treat hypertension as it generates NO, resulting in vasodilation of arterioles and venules.
NO gas inhalation can reduce pulmonary artery pressure and improve lung perfusion.

NO in Disease

NO plays a role in vascular effects, acting as a vasodilator and regulating blood pressure.
NO inhibits platelet aggregation.
NO has antioxidant properties, protecting from free radicals.
High levels of NO can contribute to health complications like septic shock, by causing extensive vasodilation and leading to low blood pressure.
Infection and inflammation can induce iNOS, increasing NO production which can exacerbate cell injury

NO in the CNS and PNS

In the central nervous system (CNS), NO acts as a neurotransmitter, enhancing neurotransmission.
In the peripheral nervous system (PNS), non-adrenergic, non-cholinergic receptors release NO, promoting vasodilation.

Respiratory disorders

NO is used to treat pulmonary hypertension.

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