The phenomenon of "pre-ischaemic conditioning" in the brain only partly involves the NMDA receptor: a magnetic resonance study.
We have investigated in more detail our previous observations on a form of ischaemic pre-conditioning "metabolic adaptation", i.e.--that sequential metabolic insults (hypoxia followed 40 min later by combined hypoxia + hypoglycaemia, or vice versa) are less injurious (monitored by increased [Ca2+]i and decreased PCr) than the immediate combined insult. We have now observed that the "adaptation" occurs between 10 and 20 min. Pre-treatment of the tissues with 10 microM-MK801 showed that it had no effect on the increase in [Ca2+]i caused by the sequential insult and only partially blocked the increase observed by exposure to the immediate combined insult. Exposure to both the delayed and immediate combined insults with low extracellular Ca2+ resulted in a two-fold increase in [Ca2+]i, similar to the increase observed with normal extracellular Ca2+ in the presence of MK801. The results are discussed in terms of the possible origins of the increases in [Ca2+]i.
Prior
Malcolm
M
Sir Peter Mansfield Magnetic Resonance Centre, School of Physics & Astronomy, University of Nottingham, NG7 2RD, UK.
Thatcher
Nicola
N
Morris
Peter
P
Reese
Torsten
T
Bachelard
Herman
H
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002545:Brain Ischemia / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000378:metabolism; D016291:Dizocilpine Maleate / Q000378:metabolism; D004533:Egtazic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D006168:Guinea Pigs; D066298:In Vitro Techniques; D019194:Ischemic Preconditioning; D008279:Magnetic Resonance Imaging; D009543:Nifedipine / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate
C080781:1,2-bis(2-aminophenoxy)ethane-5,5'-difluoro-N,N,N',N'-tetraacetic acid acetoxymethyl ester; D002121:Calcium Channel Blockers; D016194:Receptors, N-Methyl-D-Aspartate; D004533:Egtazic Acid; D016291:Dizocilpine Maleate; D009543:Nifedipine; D002118:Calcium