|
|
|
|
 |
|||
|
|||
Distributions of aspartate aminotransferase and malate dehydrogenase activities in rat retinal layers
CD Ross and DA Godfrey
Aspartate aminotransferase (AAT), an enzyme interconverting glutamate and aspartate, has been suggested to be a marker for glutamatergic and/or aspartatergic neurons. However, AAT, glutamate, and aspartate are also involved in cellular metabolism, e.g., the malate-aspartate shuttle. To investigate the extent to which AAT might be involved in these several functions in retina, the distribution of AAT activity in rat retinal layers was compared to that of malate dehydrogenase (MDH), an enzyme of aerobic metabolism proposed to be physically complexed with AAT in the malate-aspartate shuttle mechanism. The distribution of AAT activity in retinal layers closely paralleled that of MDH (correlation coefficient AAT versus MDH = 0.93). AAT activity was proportionately higher than MDH in the photoreceptor inner segments, containing a high density of mitochondria, and in the outer plexiform layer (OPL), containing photoreceptor terminals and bipolar and horizontal cell processes. The amount of total AAT activity in the inner segments related to the mitochondrial isoenzyme is almost twice that in the other layers tested, including the OPL. The correlation between AAT and MDH activities is consistent with AAT involvement in retinal energy metabolism, although other functions, such as neurotransmission, are possible.
Volume 33,
Issue 7,
pp. 624-630,
07/01/1985
Copyright © 1985 by The Histochemical Society
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
| Guidelines | Subscriptions | About | exPRESS - Current - Archive | Business Information | Contact |