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==What is Arginine?==

==What is Arginine?==

Arginine is an '''essential amino acid''' for dogs and cats. It is classified as a '''gluconeogenic''' amino acid and contains a positively charged nitrogen side chain that can be used as a binding site for other molecules. Dietary arginine is absorbed by a dibasic amino acid transporter in the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] (particularly the [[Jejunum - Anatomy & Physiology|jejunum]]) and plasma arginine is actively reabsorbed in the [[Nephron Microscopic Anatomy#Proximal Tubule|proximal tubule]] of the kidney. Species that do not require dietary arginine (such as humans) are able to endogenously synthesise adequate amounts of this amino acid through the conversion of glutamate into ornithine; ornithine is ultimately converted into arginine in the urea cycle through the activity of pyrroline-5-carboxylate synthase and ornithine aminotransferase. Low activity of these enzymes are found in dogs and cats<ref name="Burns">Burns RA, et al.  Arginine: An Indispensable Amino Acid for Mature Dogs. J Nutr 1981; 111:1020-1024.</ref><ref name="Morris">Morris JG. Nutritional and Metabolic Responses to Arginine Deficiency in Carnivores J Nutr 1985;115:524-531.</ref>. '''Dogs and cats have an absolute requirement for dietary arginine'''.

Arginine is an '''essential amino acid''' for dogs and cats. It is classified as a '''gluconeogenic''' amino acid and contains a positively charged nitrogen side chain that can be used as a binding site for other molecules. Dietary arginine is absorbed by a [[Nutrition Glossary#Dibasic Amino Acids|dibasic amino acid]] transporter in the [[Small Intestine Overview - Anatomy & Physiology|small intestine]] (particularly the [[Jejunum - Anatomy & Physiology|jejunum]]) and plasma arginine is actively reabsorbed in the [[Nephron Microscopic Anatomy#Proximal Tubule|proximal tubule]] of the kidney. Species that do not require dietary arginine (such as humans) are able to endogenously synthesise adequate amounts of this amino acid through the conversion of glutamate into ornithine; ornithine is ultimately converted into arginine in the urea cycle through the activity of pyrroline-5-carboxylate synthase and ornithine aminotransferase. Low activity of these enzymes are found in dogs and cats<ref name="Burns">Burns RA, et al.  Arginine: An Indispensable Amino Acid for Mature Dogs. J Nutr 1981; 111:1020-1024.</ref><ref name="Morris">Morris JG. Nutritional and Metabolic Responses to Arginine Deficiency in Carnivores J Nutr 1985;115:524-531.</ref>. '''Dogs and cats have an absolute requirement for dietary arginine'''.