Adrenergic Receptors in the Mechanism of Regulation of Mitochondrial and Cytoplasmic Enzymes of Cardiomyocytes by Catecholamines.

Abstract

We studied the role of adrenoceptors in the regulation of activity of mitochondrial and cytoplasmic enzymes in cardiomyocytes by catecholamines and their metabolites. Different types of adrenergic receptors (AR) agonists acting either on both α- and β-AR or selectively on α- or β-AR, as well as quinoid metabolites of catecholamines were used. It was found that the activating effect of β-AR agonist isadrin (isoproterenol) on succinate dehydrogenase of the mitochondria in the heart is prevented by β-adrenergic blockade. The activating effect of dopamine, epinephrine, and isoproterenol on cytochrome C-oxidase and the inhibitory effect of dopamine, norepinephrine, epinephrine, and isoproterenol on Mg-activated ATPase was not mediated by adrenoreceptors. Hormones of the sympathoadrenal system epinephrine, dopamine, norepinephrine, isoproterenol, and catecholamine metabolites (adrenochrome and adrenoxyl) modulating activity of the respiratory chain enzymes of mitochondria in the heart regulate the processes of tissue respiration by transferring mitochondria into a state of "loose" phosphorylation and respiration coupling. Epinephrine as a β-AR agonist increased activity of cytosolic enzymes catalyzing metabolism of purine nucleotides (adenosine deaminase and AMP deaminase), enzymes of antioxidant defense (glutathione peroxidase and catalase), and the level of malondialdehyde and diene conjugates. β-AR blockade with metoprolol abolished the activating effect of epinephrine on glutathione reductase, glutathione peroxidase, and catalase and reduced the level of malondialdehyde and diene conjugates.