Sensing epinephrine

Wu Y, Feng X, Zhou S, Shi H, Wu H, Zhao S, Song W (2013) Sensing epinephrine with an ITO electrode modified with an imprinted chitosan film containing multi-weilled carbon nanotubes and a polymerized ionic liquid. Microchim Acta 180 1325-1332. doi 10.1007/ s00604-013-1063-y... 

Regardless of the untested merits of the above work, methylation as a first step in the deactivation of noradrenaline in the body is just as plausible as is the evidence that methylation is the final step in the synthesis of adrenaline. The evidence for and against this route of synthesis has been discussed previously in this review. Tainter etal. (155) reported that in dogs under phenobarbital anesthesia Z-arterenol had a pressor activity 1.7 times that of Z-epinephrine. In this sense then, methylation might be considered a process of inactivation. However, they found in contrast that the acute toxicity of Z-epinephrine (LDso) was about four times that of Z-norepinephrine (114) 155). 

In the past, beta blockers were considered detrimental in patients with heart failure.60 As indicated in Chapter 20, these drugs decrease heart rate and myocardial contraction force by blocking the effects of epinephrine and norepinephrine on the heart. Common sense dictated that a decrease in myocardial contractility would be counterproductive in heart failure, and beta blockers were therefore contraindicated in heart failure.60,69 It is now recognized that beta blockers are actually beneficial in people with heart failure because these drugs attenuate the excessive sympathetic activity associated with this disease.56,64 As indicated earlier,... 

G-protein-coupled receptors (GPCRs), also known as seven transmembrane receptors (7TMs), are the largest known superfamily of proteins. They are involved in all types of responses to stimuli, from intercellular communication to the senses of vision, taste, and smell. They respond to diverse ligands ranging from photons (e.g., rhodopsin. Fig. 1) to small molecules (e.g., binding of epinephrine to the f52-adrenergic receptor) and... 

When narrowly defined, the biogenic amines comprise only epinephrine, norepinephrine, and dopamine. However, in a broader and more practical sense, serotonin, histamine, and acetylcholine are also included. 

Opiates snch as morphine and codeine are thonght to enhance the release by nenrons of the nenrotransmitter dopamine the release of dopamine leads to a sense of enphoria. These drugs are addictive and are often abused. In general, all antipsychotic medications work by blocking dopamine receptors in the forebrain. Nicotine mimics the action of the nenrotransmitter acetylcholine at receptors having to do with the transmission of signals between antonomic nerve cells and skeletal muscle, see also Caffeine Epinephrine Methylphenidate Neurochemistry Neurotransmitters Norepinephrine. 

Am. Epinephrine is a polypeptide synthesized in the adrenal cortex. It is released very quickly by any sudden environmental change sensed by the central nervous system, the fight or flight reflex. It stimulates glycogenolysis in both liver and muscle cells. It is also under control over long periods of time by cells in the hypothalamus of the brain which are sensitive to the blood concentration of glucose. Lowered glucose concentration will raise the epinephrine level. 

Fever elevates the blood GSH index (17-20). The degree of temperature elevation and the duration of hyperpyrexia cannot be correlated with the level of the GSH concentration. The mechanism underlying this effect of fever is not known the coincident elevated metabolic rate is not responsible because experimental hjrperthyroidism in animals lowers the blood GSH index (21-25). Stress in a general sense is perhaps a factor since electric and insulin shock therapies both raise the index after 2 to 6 hr., as do injections of epinephrine and insulin following a similar time interval (26-29). However, ACTH injections in normal man may cause no change or may lower the GSH concentration (30-38). The elevating effect of fever might simply be related to accelerated protein catabolism. 

Epinephrine administered intramuscularly and by venous infusion lowers plasmatic kininogen in man and in rabbit, whilst nor-epinephrine is inactive in this sense. Decrease of kininogen (that is, release ofiki-nins) is perhaps another metabolic feature of epinephrine, and is appears to be correlated to stimulation of adrenergic beta-receptors. As an indirect evidence of this, we can consider the results of researches by means of isoproterenol and beta-adrenergic blocking agents. 

In another work lacosamide based MIPs of methacrylic acid monomers were used for the solid-phase extraction of the template from rat plasma before LC analysis and the results revealed a recovery of over 98% for the SPE and the LOD and LR of the method were evaluated to be 0.03 pg mL and 0.1-100 pg mL [244]. B. B. Prasad et al. reported the MIP-based SPE of epinephrine and detection of the same through an MIP based sensing device in plasma cerebrospinal fluids. They reported the reaction of functionalized multiwalled carbon nanotubes (MWCNTs-COCl)] as a monomer with N-hydroxy phenylmaleimide and used glycoldimethylacrylate as the cross-linking agent. The LOD of the hyphenated method was reported to be 0.002 ng mL [245]. In another study M. Moein and co-workers developed MIP cartridges to be used in combination with HPLC for facile analysis of human insulin in plasma and urine. They used insulin as the template, in the reaction between meth-acrylicacid monomer and ethylene eglycol dimethacrylate cross-linker. The reaction initiation was achived by 2,2/-azobisisobutyronitrile. The overal results showed LODs of 0.2 ng mL in plasma and 0.03 ng mL in urine with recovery factors over 87% [246]. 

Agboola BO, Vilakazi SL, Ozoemena KI (2008) Electrochemistry at cobalt(II) tetrasulfophthalocyanine multi-walled carbon nanotubes modified glassy earbon electrode a sensing platform for efficient suppression of ascorbic acid in the presence of epinephrine. J Solid State Electrochem 13 1367-1379... 

A specific example worth exploring is the EC reaction. Such an example of this process is the modification of a glassy carbon electrode with an Osmium polymer, [Os(bpy)2(PVP)ioCl]Cl and Nafion prepared by drop-coating, producing a doublelayer membrane modified electrode [9]. In this case the modified electrode was explored towards the sensing of the neurotransmitter epinephrine (EP) [9]. Figure 2.19 shows the voltammetric response of the electroactive polymer (curves A and B in Fig. 2.19) where upon contact with epinephrine (curve C in Fig. 2.19) a reduction in the back peak coupled with an increase in the forward wave is evident. The process can be described as ... 

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