Indicators
An inorganic compound composed of a single nitrogen atom covalently bonded to three hydrogen atoms that is an amidase inhibitor and neurotoxin. It is both manufactured and produced naturally from bacterial processes and the breakdown of organic matter. Ammonia is used in many industrial processes, and as a fertilizer and refrigerant. It is characterized as a colorless gas or compressed liquid with a pungent odor and exposure occurs by inhalation, ingestion, or contact.
Indicators
A non-essential amino acid. In hepatocytes, L-citrulline is synthesized in the urea cycle by the addition of carbon dioxide and ammonia to ornithine. L-citrulline is converted into L-arginine by the enzymes argininosuccinate synthetase and argininosuccinate lyase in the presence of L-aspartate and ATP. Subsequently, L-arginine is converted to nitric oxide by nitric oxide synthase and L-citrulline is regenerated as a by-product.
Indicators
A nonessential amino acid. Glutamine can donate the ammonia on its side chain to the formation of urea (for eventual excretion by the kidneys) and to purines (necessary for the synthesis of nucleic acids). Glutamic acid-to-glutamine conversion, in which an ammonia group is added to glutamic acid (catalyzed by glutamine synthase), is of central importance in the regulation of toxic levels of ammonia in the body. This agent is a substrate for the production of both excitatory and inhibitory neurotransmitters (glutamate and GABA) and is also an important source of energy for the nervous system. Glutamine may become a conditionally essential amino acid during certain catabolic states.
Indicators
A nitrogenous compound containing a carbonyl group attached to two amine groups with osmotic diuretic activity. In vivo, urea is formed in the liver via the urea cycle from ammonia and is the final end product of protein metabolism. Administration of urea elevates blood plasma osmolality, resulting in enhanced flow of water from tissues, including the brain, cerebrospinal fluid and eye, into interstitial fluid and plasma, thereby decreasing pressure in those tissues and increasing urine outflow.