Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acid-base homeostasis depends on glutamine flow from producer organs to those capable of generating bicarbonate. Glutamine oxidation, the prerequisite metabolic transformation, can be expressed by many sites; however, net base generation requires that glutamine flow be directed to a specific organ, the kidney. Normally, glutamine flows from the periphery to the splanchnic bed, providing a major fuel and supporting ureagenesis. Glutamine flow in chronic metabolic acidosis, on the other hand, is rerouted to the kidneys; asymmetrical distribution of NH+4 and HCO3- into the urine and renal vein subserves restoration of alkaline reserves. Clearly, glutamine flows in accordance with physiological demands, yet little is known of the regulatory mechanisms. As a model, chronic metabolic acidosis alters two aspects of this vital flow, its direction and magnitude. Characteristically the direction of flow is away from the splanchnic bed and into the kidneys associated with a marked fall in arterial glutamine concentration, restoring arterial level returns flow to the splanchnic bed sink. Thus glutamine homeostasis is sacrificed to impart direction to interorgan glutamine flow. Although multiple sites contribute to glutamine homeostasis, of great strategic importance is the potent hepatic glutaminase flux activated by portal venous NH+4 fed forward by gut metabolism; local hydrogen ion concentration modulates the effectiveness of this activator. Acute regulation of flow direction can be exerted by the lungs in determining the prevailing pCO2 and cellular acidity; respiratory compensation in chronic acidosis allows the expression of hepatic glutaminase, thereby suppressing arterial glutamine concentration. The enormous magnitude of glutamine flowing from muscle to the kidneys is supported by adaptive increases in glutamine synthetase and mitochondrial glutaminase, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
 ...
PMID:Interorgan glutamine flow in metabolic acidosis. 332 41

Human cerebral cortex was studied immunocytochemically by light and electron microscopy using antibodies against glial fibrillary acidic protein (GFAP) and glutamine synthetase (GS). Glial fibrillary acidic protein-positive cells and processes were present in both cortex and white matter, but in contrast glutamine synthetase-positive cells and processes were present only in cortex. Cell bodies which contained glutamine synthetase had typical ultrastructural features of protoplasmic astrocytes. Glutamine synthetase-positive processes were often present near asymmetrical synapses in the neuropil. These processes often contained mitochondria, but not glial filaments, and were different from unlabelled astrocytic processes, which seldom contained mitochondria, but had large numbers of glial filaments. Glutamine synthetase immunoreactivity therefore affords a means of distinguishing between these two types of astrocytic processes in the human cerebral cortex.
 ...
PMID:Distribution of glial fibrillary acidic protein and glutamine synthetase in human cerebral cortical astrocytes--a light and electron microscopic study. 790 86