Simultaneous determination of plasma noradrenaline and adrenaline kinetics

Abstract

Liquid chromatographic fractionation and detection of exogenous radiolabelled and endogenous catechols was used to examine simultaneously the plasma kinetics of noradrenaline and adrenaline in the conscious rabbit. Plasma clearances and release of noradrenaline and adrenaline into plasma were compared before and during nitroprusside-induced hypotension and 2-deoxyglucose-induced glucopenia, stimuli purported to differentially affect catecholamine release from sympathetic neurons and the adrenal medulla. Plasma concentrations of dihydroxyphenylglycol (DHPG) were also measured to assess presynaptic sympathetic function. Plasma clearances of adrenaline correlated with, but were significantly less than those of noradrenaline. Plasma clearances of both catecholamines showed significant decreases during nitroprusside-induced hypotension and 2-deoxyglucose-induced glucopenia. Glucopenia and hypotension increased the release into plasma of noradrenaline and adrenaline, but the adrenaline response relative to the noradrenaline response was greater during glucopenia than during hypotension. Plasma DHPG concentrations increased during glucopenia and hypotension, consistent with increased neuronal reuptake of noradrenaline and therefore a neuronal source--as opposed to an adrenal source--of most of the noradrenaline appearing in plasma during the stimuli. The increase in plasma DHPG relative to that of noradrenaline was greater after 2-deoxyglucose than after nitroprusside suggesting that the presynaptic handling of noradrenaline during glucopenia was different from that during hypotension or that the two stimuli released DHPG from regionally distinct sources.

Responses of the Hypothalamopituitary Adrenal Axis and the Sympathoadrenal System to Isolation/Restraint Stress in Sheep of Different Adiposity

“…The catechols were first extracted from plasma using alumina adsorption, then separated by HPLC and the amounts were quantified by electrochemical detection as previously described [42]. Recovery of the extraction procedure was determined using the internal standard, dihydroxybenzylamine.…”

Noradrenaline, but Not Neuropeptide Y, Is Elevated in Cerebrospinal Fluid from the Third Cerebral Ventricle following Audiovisual Stress in Gonadectomised Rams and Ewes

“…The catechols were first extracted from CSF using alumina adsorption, then separated by HPLC and the amounts were quantified by electrochemical detection as previously described [28]. The chromatographic system consisted of a Model 480 High Precision Pump, Model Gina autosampler, Model STH 585 column oven, Chromeleon 3.03 Chromatography Data System (Dionex, Germering, Germany), Model 5100A coulometric detector equipped with a Model 5021 conditioning cell and a Model 5011 analytical cell (Environmental Sciences Associates, Mass., USA) and a 25-cm Altex Ultrasphere column (ODS 4.6 mm × 25 cm, 5-µm particle size, Beckman Instruments, Calif., USA).…”

Thoracic Epidural Anesthesia During Coronary Artery Bypass Surgery

“…Plasma concentrations of endogenous and radiolabeled NE and the metabolite DHPG were determined by high-performance liquid chromatography with electrochemical detection, a method that closely mimics that of Medvedev et al (17). On completion of each patient, samples were centrifuged at 4°C and plasma separated for storage at -80°C until assayed.…”