[Physiological and pharmacologic studies of the adrenal medulla by the measurement of plasma catecholamine levels].
The new techniques for the assay of the plasma catecholamines: noradrenaline, dopamine and, most importantly, adrenaline, because of their sensitivity and precision, have provided new information about the physiology and the pharmacology of the adrenal medulla in animals and in man. The most effective of these new techniques are the radioenzymatic techniques. The activation of the adrenal medulla in the dog or the rat appears to be frequency-dependent by maintaining a fixed concentration ratio in the systemic circulation of 4/1. In this way, it is possible to quantify the pharmacological effects of various substances for a given frequency and to evaluate their impact on the neuro-neuronal or neuro-humoral sympathetic system. In this context, the use of pithed rats, with or without adrenalectomy, is particularly useful. This model can be used to demonstrate that the global electrical activation of the sympathetic system results in a preferential stimulation of adrenaline secretion (1,000%) compared with 150% for noradrenaline secretion. Such a global activation never occurs in clinical or experimental pathology, except for activation of a baro-reflex, acidosis or hypoglycaemia. Thus it is possible that there is a separate physiological regulation of the neuro-neuronal sympathetic axis and the neuro-adrenal sympathetic axis. Neuro-neuronal regulation is sensitive to central manipulations, but especially to peripheral presynaptic stimulations and inhibitions. Neuro-adrenal regulation is particularly sensitive to inhibition by centrally acting alpha 2 type drugs, such as clonidine, but also, unlike the sympathetic neurones, to substances with a direct peripheral effect such as calcium antagonists.
Lhoste
F
F
D000313:Adrenal Medulla / Q000187:drug effects / Q000378:metabolism*; D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D002395:Catecholamines / Q000097:blood*; D002628:Chemoreceptor Cells / Q000187:drug effects; D004837:Epinephrine / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007003:Hypoglycemia / Q000378:metabolism; D007008:Hypokalemia / Q000503:physiopathology; D011311:Pressoreceptors / Q000187:drug effects; D013564:Sympathetic Nervous System / Q000378:metabolism
D000318:Adrenergic beta-Agonists; D002395:Catecholamines; D004837:Epinephrine
Etudes physiologiques et pharmacologiques de la médullo-surrénale par la mesure des taux plasmatiques des catécholamines.