Document Detail

Ammonium exposure and pyruvate affect the amino acid metabolism of bovine blastocysts in vitro.
MedLine Citation:
PMID:  15056778     Owner:  NLM     Status:  MEDLINE    
The accumulation of ammonium is a major artefact of in vitro embryo culture. This study has examined ammonium production and potential mechanisms of disposal in preimplantation bovine blastocysts. Embryos were produced by in vitro maturation and fertilisation of oocytes, and cultured in synthetic oviduct fluid containing amino acids and BSA (SOFaaBSA). Ammonium/urea concentrations were determined enzymatically. Amino acid appearance/disappearance 'profiles' of single blastocysts were determined at 0, 1.25 and 2.5 mM NH(4)Cl (with or without 0.33 mM pyruvate), and with or without 10 mM dipicolinic acid (DPCA; a glutamate dehydrogenase (GLDH) inhibitor) or 2 mM amino-oxyacetate (AOA; a transaminase inhibitor). Free ammonium was produced at a rate of 4.281 (+/-0.362) pmol/embryo/h, while urea production was undetectable. The presence/absence of pyruvate affected amino acid profiles, especially alanine appearance (P < 0.001), glutamate disappearance (P < 0.05) and overall turnover (the sum of appearance and disappearance) (P < 0.001). GLDH inhibition with DPCA had no effect on amino acid overall disappearance, but glutamate disappearance increased, while that of arginine decreased (P < 0.05). The transaminase inhibitor, AOA, depressed turnover (P < 0.05), aspartate and glutamate disappearance, and alanine appearance. Thus, bovine blastocysts release ammonium as free ions or fix them, not as urea, but as alanine, possibly glutamine and, less likely, arginine. An active role for GLDH and transaminases in regulating blastocyst amino acid metabolism was demonstrated.
Nicolas M Orsi; Henry J Leese
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Reproduction (Cambridge, England)     Volume:  127     ISSN:  1470-1626     ISO Abbreviation:  Reproduction     Publication Date:  2004 Jan 
Date Detail:
Created Date:  2004-04-01     Completed Date:  2004-06-28     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  100966036     Medline TA:  Reproduction     Country:  England    
Other Details:
Languages:  eng     Pagination:  131-40     Citation Subset:  IM    
Academic Unit of Obstetrics, Gynaecology and Paediatrics, D Floor, Clarendon Wing, Leeds General Infirmary, Belmont Grove, Leeds LS2 9NS, UK.
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MeSH Terms
Alanine / analysis,  metabolism
Amino Acids / analysis,  metabolism*
Arginine / analysis,  metabolism
Blastocyst / metabolism*
Cells, Cultured
Fertilization in Vitro
Glutamate Dehydrogenase / metabolism
Glutamic Acid / analysis,  metabolism
Pyruvic Acid / metabolism*
Quaternary Ammonium Compounds / metabolism*
Urea / analysis,  metabolism
Reg. No./Substance:
0/Amino Acids; 0/Quaternary Ammonium Compounds; 127-17-3/Pyruvic Acid; 56-41-7/Alanine; 56-86-0/Glutamic Acid; 57-13-6/Urea; 74-79-3/Arginine; EC Dehydrogenase

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