Catecholamine handling in the porcine heart: a microdialysis approach.
نویسندگان
چکیده
Experimental findings suggest a pronounced concentration gradient of norepinephrine (NE) between the intravascular and interstitial compartments of the heart, compatible with an active neuronal reuptake (U1) and/or an endothelial barrier. Using the microdialysis technique in eight anesthetized pigs, we investigated this NE gradient, both under baseline conditions and during increments in either systemic or myocardial interstitial fluid (MIF) NE concentration. At steady state, baseline MIF NE (0.9 ± 0.1 nmol/l) was higher than arterial NE (0.3 ± 0.1 nmol/l) but was not different from coronary venous NE (1.5 ± 0.3 nmol/l). Local U1 inhibition raised MIF NE concentration to 6.5 ± 0.9 nmol/l. During intravenous NE infusions (0.6 and 1.8 nmol ⋅ kg-1 ⋅ min-1), the fractional removal of NE by the myocardium was 79 ± 4% to 69 ± 3%, depending on the infusion rate. Despite this extensive removal, the quotient of changes in MIF and arterial concentration (ΔMIF/ΔA ratio) for NE were only 0.10 ± 0.02 for the lower infusion rate and 0.11 ± 0.01 for the higher infusion rate, whereas U1 blockade caused the ΔMIF/ΔA ratio to rise to 0.21 ± 0.03 and 0.36 ± 0.05, respectively. From the differences in ΔMIF/ΔA ratios with and without U1 inhibition, we calculated that 67 ± 5% of MIF NE is removed by U1. Intracoronary infusion of tyramine (154 nmol ⋅ kg-1 ⋅ min-1) caused a 15-fold increase in MIF NE concentration. This pronounced increase was paralleled by a comparable increase of NE in the coronary vein. We conclude that U1 and extraneuronal uptake, and not an endothelial barrier, are the principal mechanisms underlying the concentration gradient of NE between the interstitial and intravascular compartments in the porcine heart.
منابع مشابه
Multiparametric molecular imaging provides mechanistic insights into sympathetic innervation impairment in the viable infarct border zone.
UNLABELLED Impaired catecholamine handling in the viable infarct border zone may play an important role in ventricular remodeling and lethal arrhythmia. We sought to get further biologic insights into cardiac sympathetic neuronal pathology after myocardial infarction, using multiple tomographic imaging techniques. METHODS In a porcine model of myocardial infarction (n = 13), PET and MR imagin...
متن کاملThe effect of short-term caffeine-beet juice supplementation on catecholamine changes, lactate and Rating of Perceived Exertion before intense anaerobic activity in runners: A double-blind randomized clinical trial study
Background and Purpose: Intense anaerobic activity is used to improve anaerobic power and lactate threshold .The aim of this study was to investigate the changes in catecholamines, rating of perceived exertion and lactate supplementation with short-term caffeine and beet juice before intense anaerobic activity in runners. Methodology: In this study, 30 high performance runners (age: 27.5±3.8 y...
متن کاملTransient hypoxia alters striatal catecholamine metabolism in immature brain: an in vivo microdialysis study.
Microdialysis probes were inserted bilaterally into the striatum of 7-day-old rat pups (n = 30) to examine extracellular fluid levels of dopamine, its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), and the serotonin metabolite 5-hydroxyindoleacetic acid (5-HIAA). The dialysis samples were assayed by HPLC with electrochemical detection. Baseline levels, measured ...
متن کاملMorphine releases glutamate through AMPA receptors in the ventral tegmental area: a microdialysis study in conscious rats
Drug addiction has developed to a social illness. Changes in glutamate transmission have been recorded by the repeated administration of addictive drugs into VTA. In this investigation, In vivo microdialysis was used to study the effects of morphine on glutamate release from the ventral tegmentum area (VTA) in freely moving rats. Rats were anesthetized with chloral hydrate (350 mg/kg, i.p.) and...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The American journal of physiology
دوره 277 4 Pt 2 شماره
صفحات -
تاریخ انتشار 1999