[Role of adrenergic mechanisms in the regulation of aspartate aminotransferase isoenzyme activity in the liver of white rats].

Cytoplasmic (c) and mitochondrial (m) isozymes of aspartate aminotransferase (AAT) (EC 2.6.1.1) were isolated from white rat liver tissue by means of electrophoresis in agar gel. For the enzymes Km values, pH optima were estimated and conditions, suitable for the reaction, were studied. On the basis of activating effectiveness on c-AAT the catecholamines were arranged in decreasing order as follows: adrenaline, isadrine, noradrenaline. Towards the m-AAT the series was: noradrenaline, isadrine, adrenaline. Obsidane decreased the action of adrenaline more effectively than it did isadrine. Phentholamine did not alter the effect of noradrenalin on c-AAT, but distinctly decreased the m-AAT activity. Beta-adrenergic receptor, but not alpha-receptor, participated in regulation of the AAT isozymes activity. Adrenaline promoted and isadrine inhibited the penetration of m-AAT into cytoplasma. Obsidane increased the effect of these catecholamines. After administration of phentholamine an increase in the AAT activity was caused by an increase in content of catecholamines in the organism.