Lack of correlation between age and circulating catecholamines in hypertensive patients.
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Adult↗
Biomedical subjects
D Cousineau
Publications and source records attributed to D Cousineau.
Catecholamines in coronary sinus during exercise in man before and after training.
Coronary patients exercised on an ergometric bicycle before and after physical training. Plasma catecholamines were sampled simultaneously at the arterial and coronary sinus levels and assayed with a radioenzymatic method. The increase in the level of coronary sinus catecholamines exceeded the increase in the arterial level, indicating a liberation of catecholamines by the myocardium and an activation of the peripheral sympathetic fibers during exercise. With high work loads, these values no longer differed, suggesting that the additional increase in circulating catecholamines originate from extra-myocardial stores, presumably the adrenal medulla. Arterial catecholamine levels were significantly correlated with work loads, heart rate, changes in systolic blood pressure, and rate-pressure product. After physical training, arterial catecholamine increases for various work loads were lower; these lower elevations were associated with diminished responses in heart rate and systolic blood pressure, resulting in a lower rate-pressure product. Physical training results in diminished sympathetic responses for a given level of exercise, which could be associated with the clinical improvement of these patients.
Adult↗
[Neurogenic factors in human hypertension].
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Adrenergic beta-Agonists↗
The role of the sympathetic system in experimental and human hypertension.
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Adrenergic Fibers↗
Circulating catecholamine levels in human and experimental hypertension.
The radiometric enzymatic technique of Coyle and Henry (J. Neurochem. 21: 61-67, 1973) was adapted to the measurement of serum catecholamines. This technique requires less time than other enzymatic techniques and is sensitive to quantities as small as 25 pg. In normotensive subjects lying supine for 20 minutes serum catecholamine levels averaged 0.218 ng/ml, with no obvious sex or age difference. Under these standardized conditions, the circulating catecholamine levels for a given individual are highly reproducible on different days over a period of several months. In 22 patients with essential hypertension, circulating levels were significantly higher, with an average of 0.370 ng/ml. More than 50% of the hypertensive patients had values greater than the highest value measured in normotensives. Systolic blood pressure and heart rate were significantly higher in the hypertensive group with elevated levels of circulating catecholamines than in the hypertensive group with normal levels. In one model of experimental hypertension, produced in the rat by administration of deoxycorticosterone acetate (DOCA) and saline for 4-8 weeks, serum catecholamines were significantly elevated. These findings suggest that the sympathetic system may play an important role in maintaining an elevated blood pressure in experimental hypertension and in a significant proportion of patients with essential hypertension.
Animals↗
Changes in plasma levels of vasopressin and renin in response to haemorrhage in dogs.
1. The rabbit rectum superfused with blood or Krebs solution was used to assay vasopressin in circulating blood and in plasma extracts respectively.2. Vasopressin was released by a rapid fall in diastolic pressure of as little as 5 mmHg, and the amount of vasopressin released was proportional to the magnitude of the fall in diastolic pressure in the range studied. These results would indicate that vasopressin release follows the magnitude of the fall in diastolic pressure more closely than the actual decrease in blood volume in haemorrhagic hypotension.3. It was shown that the time required to induce an increase in circulating vasopressin is inversely proportional to the severity of the fall in diastolic pressure; this suggested that the stimulation of neurosecretory reflex arc varies with the intensity of the stimulus.4. The slight changes in plasma renin activity as well as the pattern of renin release suggested the unlikeliness of the influence of renin upon vasopressin secretion under these circumstances. On the contrary, the results suggested that the secretion of large amounts of vasopressin tended to inhibit renin release.
Animals↗
Sequestered tracer outflow recovery in multiple indicator dilution experiments.
The rapid, single injection, multiple indicator dilution technique has been, with suitable modeling of hepatic venous outflow curves, the standard approach for quantitative kinetic assessment of tracer cell entry and intracellular sequestration in the steady state, both in the in situ and the isolated perfused liver. Analysis of the underlying system yields, for a substance sequestered within liver cells, identical theoretical expressions for expected cumulative tracer fractional recovery and the steady-state fractional outflow recovery of the bulk substance whose behavior is being traced. Luxon and Forker (Am. J. Physiol. 1982; 243:G76-G89) pointed out that experimental cumulative tracer fractional recovery must match the value predicted by use of fitted model parameters in the theoretical recovery expression, and that this agreement must be regarded as the hallmark of successful fitting and modeling. Their attempts to demonstrate this agreement, by use of previously published data, were unsuccessful; this led them to question whether previous model analyses were valid. To reexamine the question we, therefore, analyzed three sets of data, on bilirubin, free fatty acid and galactose uptake, including those they had previously analyzed. We found excellent agreement between experimentally determined cumulative tracer recovery and theoretically predicted recovery. The theoretical recovery expression, now validated experimentally, provides a direct way of using fitted parameters for the rapid calculation of outflow recovery, which should prove generally useful in this area of kinetics. Demonstration of the expected agreement, moreover, restores confidence in the self-consistency of procedures used in the past to analyze multiple indicator dilution data.
Albumins↗
Plasma catecholamines following low and high doses of ouabain in anesthetized dogs with or without cervical vagotomy.
Circulating catecholamine (CA) levels in the aortic blood did not change significantly in anesthetized dogs during a period of 60 min following the rapid intravenous injection of ouabain at a dose of 10 microgram/kg, but they did increase significantly after administration of a dose of 75 microgram/kg. After bilateral cervical vagotomy, the high dose of ouabain caused a greater and earlier elevation in circulating CA levels than in intact animals along with an increased cardiac index and a lower peripheral resistance. These findings suggest the existence of a vagal inhibitory mechanism upon liberation of CA following the administration of ouabain. Although ventricular arrhythmias did occur before the increase in circulating CA, preinjection CA levels were significantly higher in animals presenting ventricular fibrillation, suggesting that a high background adrenergic tone facilitates the production of ventricular arrhythmias by ouabain. Moreover, ventricular tachycardia occurred earlier in vagotomized dogs, in which the immediate elevation of circulating CA could have been a precipitating factor for this type of arrhythmia.
Anesthesia↗
[Relation between global health and care consumption in Quebec immigrants].
This article examines the relationship between global health and care consumption in immigrants and native Quebecers. Care consumption is defined as the percentage of the population who consulted a health professional, while global health is represented by the ridit index. Mean values for ridit and care consumption do not differ significantly between immigrants and native Quebecers. The ridit increases significantly with age in native Quebecers and immigrants, indicating a progressive deterioration of global health for both groups. However, the relation between ridit values grouped for age and health professional consultation do not differ significantly between immigrants and native Quebecers. These results suggest a close link between global health and care consumption. The recently established immigrants represent an exception however. Those persons who arrived between 1980 and 1987 enjoy a better global health than native Quebecers, but consult health professionals in an identical manner.
Emigration and Immigration↗
[Global health index among immigrants in Québec].
Ridit, a global health index, was analyzed in 2,461 immigrants established in the province of Quebec and this value was compared with that obtained in 25,171 natives of Quebec. Ridit values were not significantly different between immigrants and native Quebecers, suggesting a comparable global health status in both groups. Among immigrants, women had a poorer global health index than men, a phenomenon identical to that previously observed in native Quebecers. Immigrants established since 1980 (25% of all immigrants) had a better global health index than native Quebecers, while immigrants established before 1980 were not significantly different. Immigrants represent several ethnic groups for which a global health index could not be defined.
Adolescent↗
[Personal problems related to illicit drug use in dropouts compared to students].
The consumption of psychoactive drugs and the personal problems related to substance use were evaluated among school dropouts and students. Results obtained from a self-administered questionnaire among 435 school dropouts were compared with those obtained in a previous study among 3,212 students. Drug consumption is significantly higher in school dropouts than in students. The proportions of male or female youths who report personal problems related to drug use increase progressively among the consumers of cannabis, hallucinogens, solvents and cocaine for each of the two groups. Moreover, the proportions of school dropouts or students who mention difficulties with psychotropic drugs vary inversely with the percentages of users for these products. These results suggest that the identification of the drug type represents an index for the frequency of personal problems related to drug use, and that adolescents at risk form small groups of consumers.
Adolescent↗