Nitrate Flashcards
How much nitrate generated daily from NO oxidation?
1mmol
How much daily from typical western diet?
1-2mmol
Benefits of organic nitrate supplementation
Rapid onset
Fast absorption through mucosal membrane
Lowers systemic BO
inhibits platelet aggregation
Limitations of organic nitrate supplementation
Can develop tolerance
Can cause endothelial dysfunction
Variable bioavailability when taken orally
Extensive 1st pass metabolism
What factors effect NO bioavilability
Oxidative stress (excess ROS impairs NO reduction)
Substrate/co-factor availability
Increased expression of intracellular eNOS inhibitors
Increased circulation of NOS inhibitors
retention by altered haemoglobin
What effect does calveolin-1 have
Intracellular e-NOS inhbitor
What is ADMA
NOS inhibitor
What does oxyhaemoglobin do
Acts as a nitrate reductase
What is NO generated from endogenously
L-arginine
What enzymes catalyse endogenous NO production
eNOS (endothelial)
nNOS (neuronal)
iNOS (inducible)
What are NOS enzymes dependent on
calmodulin
What do NOS use as an electron donor
NADPH
How do NOS convert arginine to NOS
5 cofactors for 5 electron oxidation of arginine to NO
Stoichiometric production of citrulline
What are nitrothiols
Storage molecules for NO, broken down to form NO
Where is dietary nitrate absorbed
GI tract
How much absorbed nitrate is in salivary glands
25%
What reduces dietary nitrate to nitrate and where
Facultative anaerobes
Dorsum of tongue
What happens to smallowed nitrite not absorbed
Acid reduction to NO in stomach
How much dietary nitrate is lost via urine
60% in first 48 hours
Action of Nitrate
Decreases BP Reduces platelet aggregation Reduced oxygen cost Increased cerebral blood flow Increased muscle contractility
Action of Nitric Oxide
Regulates vascular tone (vessel dilation and contraction)
Keeps stomach mucus thick
Neurotransmitter
Higher effect in veins than arteries
Symbol for nitrite
NO2-
Symbol for nitrate
NO3-
