title: Possible role of ascorbic acid in catecholamines-stimulated Na+-K+-adenosine triphosphatase activity of the central nervous tissues.
abstract: Using EDTA and illuminated bovine retinas homogenate it has been found that Na+-K+-ATPase was stimulated by noradrenaline (NA), dopamine (DA), cAMP and dibutyryl cAMP. Phentolamine, an alpha adrenergic antagonist and INPEA, a beta adrenergic antagonist used at the same concentrations as catecholamines (CA) depressed the stimulatory effect of NA. Phentolamine increased the stimulatory effect of DA but INPEA inhibited it. It is proposed, therefore, that DA acts on retina Na+-K+-ATPase by putative DA receptors regulated by adrenergic antagonists. Ascorbic acid (AA), 0.125-1.0 mM depressed Na+-K+-ATPase activity of retinas, rat brain cortex and cerebellum homogenates. The results are consistent with the hypothesis that CA and AA can exert their effects in the presence of EDTA. In the retina the effects of CA is mediated by cAMP and alpha receptor influencing process. AA is postulated as a factor regulating the stimulation of CA on Na+-K+-ATP-ase and thereby the turnover of neurotransmitters in the central nervous system tissues.
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001205:Ascorbic Acid / Q000502:physiology*; D002395:Catecholamines / Q000494:pharmacology*; D002417:Cattle; D002490:Central Nervous System / Q000201:enzymology*; D002531:Cerebellum / Q000201:enzymology; D002540:Cerebral Cortex / Q000201:enzymology; D066298:In Vitro Techniques; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012160:Retina / Q000201:enzymology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D013574:Synaptosomes / Q000378:metabolism
chemical_list: D002395:Catecholamines; D000255:Adenosine Triphosphate; C030704:magnesium sodium potassium ATPase; D000254:Sodium-Potassium-Exchanging ATPase; D001205:Ascorbic Acid