PubMed · 5904149
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J Häggendal. 1966. Newer developments in catecholamine assay.. https://pubmed.ncbi.nlm.nih.gov/5904149/
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The clinical importance of simultaneous analysis of 3,4-dihydroxyphenylglycol with other human plasma catecholamines has been investigated to better understand the sympathetic nervous system. However, previous reports have had analytical difficulties with both resolution and extraction. The current study uses a reversed-phase triacontylsilyl silica (C30) column under the mobile phase condition without ion-pair reagents to separate catecholamines and their metabolites, with above 91% recoveries for intra-assay, above 85% for inter-assay, and less than 10% (n=5) coefficient of variation. Lower detection limits (S/N=4) and quantification limits (S/N=6) were 40 and 100 pg/mL for norepinephrine, 3,4-dihydroxyphenylglycol, and 3,4-dihydroxyphenylalanine, 10 and 20 pg/mL for epinephrine, 10 and 40 pg/mL for dopamine. Linear ranges were from 40 to 5000 pg/mL for norepinephrine and 3,4-dihydroxyphenylalanine, from 100 to 5000 pg/mL for 3,4-dihydroxyphenylglycol, and from 10 to 2000 pg/mL for epinephrine and dopamine. The C30 column may prove clinically useful, as it provides a convenient and simultaneous method of evaluation of human plasma catecholamines.
Understanding of the mechanisms involved in the development of essential hypertension is incomplete. Many studies have demonstrated that sympathetic overactivity is involved in the development of essential hypertension. In addition, hypertensive patients, as a group, are insulin resistant. The relationship of increased sympathetic activity to insulin resistance in essential hypertension has not been adequately explained. Hypertensive subjects have been reported to have rapid gastric emptying compared to control subjects. They also have increased postprandial hypotensive responses to high carbohydrate meals compared with non-hypertensive control subjects. The author hypothesizes that essential hypertension is the result of a metabolic disregulation in which the body's glucose regulatory system splits into two separate glucose control systems with two different homeostatic set points for fasting and postprandial glucose levels. It is proposed that insulin is the principle regulator of the lower glucose set point while counter-regulatory hormones, predominantly catecholamines, as well as the rate of gastric emptying, are regulators of the upper glucose set point. The tension between these two opposing control systems results in increased sympathetic activity, increased fasting and postprandial glucose and insulin levels and an increased rate of gastric emptying in hypertension. It is hypothesized that increased sympathetic activity from these opposing regulatory systems initiates a vicious cycle that eventually leads to the development of essential hypertension. This hypothesis explains the beneficial effects of agents that either slow carbohydrate absorption or delay gastric emptying on essential hypertension and postprandial hypotension. New therapeutic strategies for treatment of hypertension are suggested by this hypothesis.
We developed an interdigitated array electrode (IDAE) consisting of a metal oxide electrode and a metal band heteroelectrode and employed it for the selective detection of catecholamines. We used an indium-tin oxide (ITO) film as the oxidation electrode of the IDAE because the ITO was able to suppress response currents from L-ascorbic acid (AA) and uric acid (UA), which are major electroactive interferents in biological fluids. However, the ITO film also suppresses the reduction of quinones including oxidized catecholamines. We developed a simple technique for fabricating our hetero IDAE, which also preserves the electrochemical properties of the ITO. When we compared hetero ITO-gold, homo ITO-ITO, and carbon-carbon IDAEs, we found that the hetero IDAE provided both high sensitivity and selectivity for DA detection. We achieved high selectivities for DA against AA and UA. The ratios of the response currents of AA and UA to DA were calculated as 6 and 5%, respectively.