Reduced imprecision of the radioenzymatic assay of plasma catecholamines by improving the stability of the internal standards

Hoffmann, J. J. M. L.; Willemsen, Jacques J.; Lenders, J. W. M.; Benraad, Th. J.

doi:10.1016/0009-8981(86)90156-7

Cited by 24 publications

(7 citation statements)

References 7 publications

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“…Plasma caffeine concentrations were measured by a reversed-phase H P L C~~ and plasma catecholamines by a radioenzymatic assay. 23 We did not measure plasma nicotine levels in this study because they were expected to be in the same range as that found in a previous study on the circulatory effects of nicotine chewing9…”

Section: Drug Tnfustonmentioning

confidence: 72%

The cardiovascular interaction between caffeine and nicotine in humans

Smits

Temme

Thien

1993

Clin Pharmacol Ther

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In a placebo-controlled, double-blind randomized design, we investigated the cardiovascular interaction between caffeine (250 mg intravenously) and nicotine (4 mg chewing gum) in 10 healthy volunteers, both under baseline conditions and during physical and mental stress (standing up and mental arithmetic). Caffeine alone induced a significant increase in blood pressure associated with a decrease in heart rate, whereas nicotine alone increased both blood pressure and heart rate. The combination of caffeine and nicotine increased systolic and diastolic blood pressure by 10.8 +/- 2.0 and 12.4 +/- 1.9 mm Hg, respectively. This pressor response did not differ significantly from the calculated additive effects of caffeine and nicotine on blood pressure, measuring 12.9 +/- 2.0 and 14.2 +/- 2.1 mm Hg, respectively. Heart rate and forearm blood flow also showed a similar response when the combination of caffeine and nicotine was compared with the calculated sum. During physical stress (standing up), blood pressure, heart rate, and plasma catecholamines increased in the placebo test. The pressor response to standing up was less pronounced after the combination of caffeine and nicotine compared with the sum of the separate effects (combination versus sum: delta diastolic blood pressure, 24.7 +/- 1.9 versus 35.2 +/- 2.6 mm Hg [p < 0.01]; delta mean arterial pressure, 22.1 +/- 2.0 mm Hg versus 28.6 +/- 1.6 mm Hg [p < 0.05]). The plasma catecholamine response did not differ between the combination and the sum of both drugs. During mental arithmetic, blood pressure, heart rate, and forearm blood flow increased in the placebo test. The forearm vasodilator response to mental stress was attenuated by the combination of caffeine and nicotine compared with the sum of both drugs (combination versus sum: delta forearm blood flow, -0.1 +/- 0.3 versus 1.4 +/- 0.5 ml/100 ml/min [p < 0.05]). We conclude that the combined administration of caffeine and nicotine shows additive effects on cardiovascular parameters during baseline conditions but less than additive effects during sympathoadrenal stimulation.

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Section: Drug Tnfustonmentioning

confidence: 72%

The cardiovascular interaction between caffeine and nicotine in humans

Smits

Temme

Thien

1993

Clin Pharmacol Ther

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“…Plasma glucose was measured with an autoanalyser using the glucose oxidase method and plasma insulin was measured in duplicate by radioimmunoassay. Plasma catecholamines were measured in duplicate using a radioenzymaticassay [5].…”

Section: Methodsmentioning

confidence: 99%

The effect of oral glucose, protein, fat and water loading on blood pressure and the gastrointestinal peptides VIP and somatostatin in hypertensive elderly subjects

Peeters

et al. 1990

Eur J Clin Investigation

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In elderly subjects blood pressure (BP) may fall after a meal. It can be reproduced by oral glucose, but the effect of fat and protein ingestion on postprandial BP has not been reported. Furthermore, we hypothesized that vasoactive gastrointestinal peptides are involved in this phenomenon. We studied 10 hypertensive elderly subjects (mean age 74 _+ 3 years) for the effects of oral glucose, fat, protein and water loading on BP in relation to plasma concentrations of vasoactive intestinal polypeptide (VIP), somatostatin and insulin. Glucose loading resulted in a decrease of mean arterial pressure by 14+ 2 mmHg (PSO-001). In contrast, the ingestion of fat, protein or water had no significant effect on BP. Somatostatin increased after fat and protein loading, whereas VIP increased only after fat loading. These data indicate that postprandial BP reduction in the elderly is related to glucose-related factors. The gut peptide VIP does not seem to play a role in this phenomenon.

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“…Blood samples for determination of plasma catecholamines were collected at time 0 and 10 minutes through an intravenous catheter which was inserted in an antecubital vein 30 minutes before the start of tilt. Plasma catecholamines were measured in duplicate using a radioenzymatic assay 5 …”

Section: Methodsmentioning

confidence: 99%

The Influence of Age and Blood Pressure on the Hemodynamic and Humoral Response to Head‐Up Tilt

Jansen

Thien

Hoefnagels

et al. 1989

J American Geriatrics Society

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It has been reported that postural hypotension in the elderly is common. However, these studies included institutionalized and more or less disabled persons. Furthermore, postural hypotension may be related to baseline blood pressure. In this study, the influence of age and blood pressure on the hemodynamic and plasma catecholamine responses to orthostatic stress was investigated in young and old normotensive and hypertensive healthy subjects. In normotensive and hypertensive elderly persons, the percentage blood pressure responses during tilt were not significantly different from that seen in young normotensives. We measured a slight decrease of systolic blood pressure and a slight increase of diastolic blood pressure. The hypertensive young patients showed an enhanced diastolic blood pressure response with no fall in systolic blood pressure, in contrast to the normotensive young subjects. Both elderly groups had a lower increase of heart rate than the young subjects. The percentage increase in norepinephrine after tilting was significantly lower in elderly hypertensives than in elderly normotensives and young hypertensives. The presence of hypertension was associated with a decrease in blood pressure, but age had no influence on the change in blood pressure during tilt. In this group of healthy elderly subjects, there was no significant orthostatic hypotension when the blood pressure course of the entire tilt test was taken into account.

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Reduced imprecision of the radioenzymatic assay of plasma catecholamines by improving the stability of the internal standards

Cited by 24 publications

References 7 publications

The cardiovascular interaction between caffeine and nicotine in humans

The cardiovascular interaction between caffeine and nicotine in humans

The effect of oral glucose, protein, fat and water loading on blood pressure and the gastrointestinal peptides VIP and somatostatin in hypertensive elderly subjects

The Influence of Age and Blood Pressure on the Hemodynamic and Humoral Response to Head‐Up Tilt

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