Catecholamines


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Catecholamines

 

pyrocatechin derivatives that participate in physiological and biochemical processes in animals and man. The catecholamines include epinephrine, norepinephrine, and dopamine.

Being hormones from the medullary layer of the adrenals and mediators of the nervous system, catecholamines reflect and determine the condition of the sympathetic division of the autonomic nervous system. They play an important role in neurohumoral regulation and neurotrophic functions and take part in the body’s metabolism and adaptive reactions to ensure the constancy of the internal environment and physiological functions (homeostasis). The effects of the catecholamines are the result of their reaction with adrenoreceptors, reactive cellular systems that react specifically with catecholamines. The a-adrenoreceptors are associated mainly with excitation; the /3-adrenoreceptors, with the inhibition of smooth muscles and with the acceleration and intensification of cardiac contractions. Catecholamines are present in blood, organs, tissues, and urine. During physical and mental exertion and in certain diseases (for example, in tumors of the adrenal medulla), the catecholamine content of the blood and urine increases sharply. Catecholamines undergo metabolic conversions (oxidative deamination, O-meth-ylation, quinoid oxidation) that lead to their inactivation or alter their physiological and biochemical properties. When functioning as mediators, the catecholamines are deposited in special granules at the nerve endings.

A number of pharmaceutical agents act on the different stages of catecholamine synthesis, release, deposition, and metabolism. For example, reserpine depletes the catecholamine reserve; par-gyline and iproniazid suppress the oxidative deamination, and Aldomet the synthesis and deposition, of catecholamines; and guanethidine and bretylium prevent the transmission of nervous impulses. These substances are used to intensify or to moderate the activity of the sympathetic nervous system.

REFERENCES

Adrenalin i noradrenalin. (Conference reports). Moscow, 1964.
Matlina, E. Sh., and V. V. Men’shikov. Klinicheskaia biokhimiia kate kholaminov. Moscow, 1967.
Manukhin, B. N. Fiziologiia adrenoretseptorov. Moscow, 1968.

G. N. KASSIL’ and E. SH. MATLINA

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The primary objective of this study was to provide epidemiologic evidence of the association between long-term air pollutants and three urinary catecholamines: epinephrine (EPI), NE, and DA.
Blood samples in both the groups were taken just after T2 measurements to assess serum catecholamine levels.
Changes in plasma catecholamine concentrations following infiltration with large volumes of local anaesthetic solution containing adrenaline.
mIBG is a catecholamine analogue that shares both the uptake and storage mechanism with norepinephrine in the adrenal gland and lacks post-synaptic activity.
Patients with functional PG, such as pheochromocytoma, usually present a triad of clinical symptoms (Menard's triad): cephalgia, tachycardia, and diaphoresis, these symptoms being mainly related to high levels of catecholamines in blood.
Glucocorticoids play a fundamental part in catecholamine metabolism, production, and release both in the healthy adrenal medulla and in pheochromocytoma cells.
Based on this study, they encouraged the use of the words "contraction band necrosis" for a specific morphofunctional entity caused by increased concentrations to catecholamines, and they calculated a histologic threshold of 37 [+ or -] 7 foci per 100 m2 tissue as an indication of severe sympathetic stress.
By immunohistochemically staining of catecholamine-synthesizing enzymes it has been shown that the enzyme pathway for catecholamines in midgut NETs is similar to that in pheochromocytomas [34].
Fung et al., "The importance of the interpretation of urine catecholamines is essential for the diagnosis and management of patient with dopamine-secreting paraganglioma," Annals of Clinical Biochemistry, vol.
[sup][1] reported that the sudden release of catecholamine from the pheochromocytoma is associated with the mechanism underlying VT.
Circulating catecholamines and complete alphaadrenergic blockade lead to tachycardia for the treatment of which the patient was started on oral propranolol 10 mg twice daily four days prior to surgery.
Pheochromocytomas are tumors of the adrenal medulla that produce and usually secrete large amounts of catecholamines often associated with high fatality rates when undiagnosed (1).