Histidine (HIS) is an essential amino acid investigated for therapy of various diseases, used for tissue protection in transplantation and cardiac surgery, and as a supplement to increase muscle performance. The data presented in the review show that HIS administration may increase ammonia and affect the level of several amino acids. The most common are increased levels of alanine, glutamine, and glutamate and decreased levels of glycine and branched-chain amino acids (BCAA, valine, leucine, and isoleucine). The suggested pathogenic mechanisms include increased flux of HIS through HIS degradation pathway (increases in ammonia and glutamate), increased ammonia detoxification to glutamine and exchange of the BCAA with glutamine via L-transporter system in muscles (increase in glutamine and decrease in BCAA), and tetrahydrofolate depletion (decrease in glycine). Increased alanine concentration is explained by enhanced synthesis in extrahepatic tissues and impaired transamination in the liver. Increased ammonia and glutamine and decreased BCAA levels in HIS-treated subjects indicate that HIS supplementation is inappropriate in patients with liver injury. The studies investigating the possibilities to elevate carnosine (beta-alanyl-L-histidine) content in muscles show positive effects of beta-alanine and inconsistent effects of HIS supplementation. Several studies demonstrate HIS depletion due to enhanced availability of methionine, glutamine, or beta-alanine.

• MeSH
• aminokyseliny metabolismus   MeSH
• amoniak metabolismus   MeSH
• histidin farmakologie   MeSH
• játra účinky léků   metabolismus   MeSH
• kosterní svaly účinky léků   metabolismus   MeSH
• lidé MeSH
• potravní doplňky MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH
• Názvy látek
• aminokyseliny MeSH
• amoniak MeSH
• histidin MeSH

The passage of 6 model drugs; acetylsalicylic acid, chloramphenicol, ethimizol, carbisocaine, heptacaine, and diazepam, through the blood-brain barrier, was determined in unirradiated control rats and in animals 1, 3, and 7 days after irradiation of the head only with a dose of 25 Gy from a 60Co source. The brain uptake index (BUI), which compares the uptake of the test substance with that of 3H2O 5 s after their injection into the common carotid artery, was significantly increased in comparison with unirradiated controls 7 days after irradiation, for all substances tested except for ethimizol. For acetylsalicylic acid and chloramphenicol it was also significantly increased in the other time intervals. The less lipophilic substances showed a greater relative increase of BUI than the more lipophilic ones.

• MeSH
• Aspirin farmakokinetika   MeSH
• chloramfenikol farmakokinetika   MeSH
• diazepam farmakokinetika   MeSH
• etimizol farmakokinetika   MeSH
• hematoencefalická bariéra účinky záření   MeSH
• inbrední kmeny potkanů MeSH
• karbamáty farmakokinetika   MeSH
• kraniální ozáření * MeSH
• krysa rodu Rattus MeSH
• mozek metabolismus   MeSH
• piperidiny farmakokinetika   MeSH
• radioizotopy kobaltu MeSH
• regresní analýza MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• Aspirin MeSH
• carbizocaine MeSH Prohlížeč
• chloramfenikol MeSH
• diazepam MeSH
• etimizol MeSH
• heptacaine MeSH Prohlížeč
• karbamáty MeSH
• piperidiny MeSH
• radioizotopy kobaltu MeSH