Catecholamines


Also found in: Dictionary, Thesaurus, Medical, Wikipedia.

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

References in periodicals archive ?
In this case, before the night of admission, the only symptoms were occasional palpitations, worsening over a period of several years, which in retrospect were always associated with increased abdominal pressure which apparently pushed on the tumor to secrete a surge of excess catecholamines.
Percutaneous biopsy of adrenal and extra-adrenal retroperitoneal lesions: Beware of catecholamine secreting tumours
In the case of catecholamines, the metabolism and clearance from circulation throughout the body is facilitated by the COMT (catechol-0-methyltransferase) enzyme.
The most common reasons for biochemical testing are: (a) presence of both hypertension and episodic symptoms of catecholamine excess (e.
Stimuli stimulate the release of catecholamines at nerve endings and prevent their reabsorption into the nerve endings vesicles.
Adipocyte lipolysis is physiologically stimulated by catecholamine hormones.
One of the largest series is from the Mayo Clinic with most presenting as incidental findings or mass effect and only 20% catecholamines (8).
Phaeochromocytoma and catecholamine induced cardiomyopathy presenting as heart failure.
In contrast to cortisol secretion, however, relatively few studies have characterized catecholamine responses to stress in domestic animals, partly because plasma catecholamines have been regarded as a highly variable experimental end point (Minton, 1994).
Urinary catecholamine quantitation was undertaken by HPLC on an acidified 24 hour urine collection.
The requirement for high doses of vasopressors is often considered both a poor prognostic sign and an indication of catecholamine resistance (1-6).
We conclude that, in older people, high omega-3 consumption increases insulin sensitivity, may reduce FFA mobilization by catecholamines, and reduces inflammatory markers, but did not alter endocrine responsiveness after 8 weeks.