A derivative of the amino acids glycine and arginine, important in muscle as a store of phosphate for resynthesis of ATP during muscle contraction and work.
A nonprotein nitrogenous substance in muscle tissue combines with phosphate to form phosphocreatine which serves as a storage form of high-energy phosphate required for muscle contraction.
A compound of nitrogen found in the muscles, produced by protein metabolism and excreted as creatinine.
A metabolite in muscle which is synthesized from glycine and arginine and which can be phosphorylated to form creatine phosphate.
Creatine is a naturally occurring nitrogenous compound that is consumed in the diet and produced in the body. An osmotically active substance, creatine is absorbed or synthesized in the liver, kidneys, and pancreas from the amino acid precursors — glycine, methionine, and arginine. Once synthesized, creatine is transported to the muscle and heart via the bloodstream where it plays an integral role in energy metabolism. Dietary sources of creatine include meat, fish, and poultry. A mixed diet typically contains approximately 1.5 to 2.0 g creatine daily. Oral ingestion of creatine naturally depresses biosynthesis of the compound. Nonetheless, individuals following a vegetarian diet typically have lower intramuscular levels of creatine compared to nonvegetarians.
Compound produced in the body and found in muscle and blood, the phosphate form (phospho-creatine) of which is an energy source for muscle flexion.
A compound normally stored in muscle tissue as phosphocreatine; found in small quantities in urine and in larger quantities in children and pregnant women.
A product of protein metabolism found in muscle. Its phosphate, creating phosphate (phosphocreatine, phosphagen; acts as a store of high-energy phosphate in muscle and serves to maintain adequate amounts of ATP (the source of energy for muscular contraction).
A nitrogenous substance, methyl-guanidine-acetic acid. The adult human body contains about 120 grams, 98 per cent of which is in the muscles. Much of the creatine in muscles is combined with phosphoric acid as phosphocreatine, which plays an important part in the chemistry of muscular contraction.
A colorless, crystalline substance that can be isolated from various animal organs and body fluids. It combines readily with phosphate to form phosphocreatine (creatine phosphate), which serves as a source of high-energy phosphate released in the anaerobic phase of muscle contraction. Creatine may be present in a greater quantity in the urine of women than in that of men. Creatine excretion is increased in pregnancy and decreased in hypothyroidism.
A molecule that contains nitrogen and is employed by the organism to produce the compound known for its high-energy properties, phosphocreatine (PCr).
Creatine, derived from protein synthesis and stored within the muscular tissues, serves as an energy reservoir facilitating muscle contractions. A portion of creatine undergoes conversion into creatinine, which subsequently enters the bloodstream. In the presence of healthy kidneys, this creatinine is effectively filtered out and excreted in urine. However, impaired kidney function can result in abnormal elevation of creatinine levels in the bloodstream.