What does the nitrate-nitrite-NO pathway generate independently of our own host enzymes?

What does the nitrate-nitrite-NO pathway generate independently of our own host enzymes?

• A. Nitric oxide
• B. Ammonia
• C. Hydrogen sulfide
• D. Nitrous oxide

Answer: (A)

This question tests that the oral microbiota can generate nitric oxide without relying on human enzymes. Dietary nitrate is taken up in the mouth and reduced by nitrate-reducing bacteria to nitrite. That nitrite can then be further reduced to nitric oxide by bacterial nitrite reductases, or chemically under acidic conditions, providing NO independently of host nitric oxide synthase. This NO has antimicrobial effects locally and can influence systemic physiology after absorption. The other compounds come from different microbial processes: ammonia from urease activity or amino-acid deamination, hydrogen sulfide from sulfur-containing amino acid metabolism, and nitrous oxide from other denitrification steps not representative of the primary nitrate-nitrite-NO axis in this context. So the product generated independently of our own enzymes is nitric oxide.

This question tests that the oral microbiota can generate nitric oxide without relying on human enzymes. Dietary nitrate is taken up in the mouth and reduced by nitrate-reducing bacteria to nitrite. That nitrite can then be further reduced to nitric oxide by bacterial nitrite reductases, or chemically under acidic conditions, providing NO independently of host nitric oxide synthase. This NO has antimicrobial effects locally and can influence systemic physiology after absorption. The other compounds come from different microbial processes: ammonia from urease activity or amino-acid deamination, hydrogen sulfide from sulfur-containing amino acid metabolism, and nitrous oxide from other denitrification steps not representative of the primary nitrate-nitrite-NO axis in this context. So the product generated independently of our own enzymes is nitric oxide.