SEARCH RESULTS FOR: Nitrous-Oxide

Nitrous Oxide

Nitrous Oxide: Mechanism of action and clinical effects Binds to & activates γ- aminobutyric acid (GABAA) receptor ↑ Chloride ion influx into the neuron Possible activation of Calmodulin–Nictric Oxide Synthase–Cyclic Guanosine Monophosphate dependent Protein Kinase pathway (exact mechanism unclear) ↑ Neurotransmission Inhibition Minimal Sedation (Anxiolysis) Authors: Parthiv Amin Andre Skipper Tracey Rice Reviewers: Billy Sun, Joseph Tropiano Run Xuan (Karen) Zeng Luiza Radu Michael Chong* Leyla Baghirzada* * MD at time of publication N-methyl-D-aspartate (NMDA) receptor antagonist (inhibitor) Closes NDMA receptor channels Inhibit ionic currents ↓ Central nervous system excitability Analgesia Hyperhomocysteinemia (Excessive build-up of homocysteine due to lack of conversion to methionine) ↑ Reactive oxygen species (ROS) & endothelial damage ↑ Coagulation & endothelial adhesion ↑ Atherosclerosis & thrombosis ↑ Risk of perioperative cardiovascular complications (Myocardial ischemia & myocardial infarction) Pyramidal Cell Vacuole Reaction: Swelling of endoplasmic reticulum & mitochondria Rapidly reversible pyramidal cell neurotoxic vacuole reaction in posterior cingulate/retrosplenial cortex (PC/RSC) Neurotoxicity with prolonged use Lack of methionine impairs ability to produce S- adenosylmethionine (SAM) Lack of SAM (helps regulate folate production) causes diversion of folate to methionine production Lack of folate impairs thymidine production Lack of thymidine (crucial nucleotide in DNA synthesis) impairs DNA synthesis Megaloblastic Anemia Nociception modulation (Detection & transmission of harmful stimuli) Neurons stimulation in periaqueductal grey area (PAG) of midbrain Endogenous opioid peptides (EOPs) release EOP activates peripheral opioid receptors GABA-ergic nuclei of pons Inhibits activity of noradrenergic pathway (flight or flight response) Descending noradrenergic pathway activation in dorsal horn of spine Nitrous Oxide (N2O) irreversibly oxidizes (inactivates) vitamin B12 (cobalamin) Vitamin B12 no longer available as cofactor for methionine synthase Irreversible inhibition of methionine synthase (converts homocysteine to methionine) ↓ Pain signals between primary & second order afferent sensory neurons (direct pain inhibition) Upregulation of GABA interneurons (Indirect pain inhibition) GABA release further ↓ pain signals Analgesia Legend: Pathophysiology Mechanism Sign/Symptom/Lab Finding Complications Published Sept 20, 2017; updated Feb 24, 2025 on www.thecalgaryguide.com