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At least 379 records · Page 21Linked to original sources
PubMed1993

Role of endothelin in heart function in health and disease.

A comprehensive review of the literature has revealed that endothelins belong to a family of vasoactive peptides which are formed and released from the endothelium. By producing constriction of the coronary arteries and peripheral blood vessels, endothelins are known both to reduce coronary bloodflow and increase blood pressure and thus can be seen to affect heart function adversely. On the other hand, endothelins are capable of producing positive inotropic and chronotropic effects by directly affecting both the myocardium and nodal tissues. Prolonged actions of high concentrations of endothelins can be seen to induce relative hypoxia in the myocardium which will eventually result in heart dysfunction. The mechanisms of actions of endothelin on smooth muscle cells and cardiomyocytes include interaction with endothelin receptors on the cell surface, activation of phospholipase C through G-proteins, and increase in the intracellular concentration of Ca2+ through the increase in phosphoinositol turnover. Endothelins were found to exert no effects on sarcolemmal Na+,K(+)-ATPase, Na(+)-Ca2+ exchange and Ca2+ pump systems nor on the sarcoplasmic reticular Ca2+ pump system and myofibrillar ATPase activities in the rat heart. Marked elevation in the levels of plasma endothelins and down-regulation of endothelin receptors in ischemia-reperfusion injury, hypertension and chronic diabetes indicate a significant role of endothelins in the genesis of heart dysfunction under different pathological conditions.

Animals↗
PubMed1993

[Fundamentals of comprehensive prevention of the post-traumatic fat embolism syndrome].

Urgent top standard provisions implemented as soon as possible after serious injuries with the aim to prevent the development of shock or treat incipient and developing shock are among the most important aspects of prophylaxis of the traumatic fat embolism syndrome (FE). These provisions comprise quantitative and qualitative replacement of blood losses, prevention of spasms of the peripheral blood vessels, restoration of the microcirculation, maintenance of the acid-base equilibrium and a normal state of coagulation, normalization of fluctuations of the post-traumatic metabolic and humoral response, blocking of pathological impulses from the site of the fracture incl. settling of the long bones; suppression of hypoxia, in particular also by artificial pulmonary ventilation; a high caloric intake to prevent excessive development of lipolysis. Surgical operations with the exception of urgent ones which form part of urgent intensive care must be postponed to the time when clinical manifestations of traumatic shock have completely subsided. The group of comprehensive prophylactic provisions comprises also pharmacological measures/drugs and substances which influence the pathogenetic basis associated with the genesis and development of the FE syndrome and the more general syndrome of post-traumatic dyslipidaemic coagulopathy resp.

Embolism, Fat↗
PubMed1996

Antiarrhythmic and anti-ischemic properties of calcium-channel antagonists.

The calcium-channel blockers are an ever-enlarging, heterogeneous group of drugs with widely variable effects on myocardium, sinoatrial and atrioventricular nodal function and conduction, peripheral blood vessels, and coronary circulation. Since the development and characterization of calcium-channel antagonists in the 1960s, these agents have become increasingly important in the treatment of many cardiovascular diseases. Nine calcium-channel blockers-nifedipine, nicardipine, amlodipine, felodipine, isradipine, nimodipine, diltiazem, verapamil, and bepridil-are all approved for use in the United States. Each major category has its own unique physiologic features. These drugs are extremely useful in the management of cardiac arrhythmias (particularly supraventricular arrhythmias) and/or ischemia. As future generations of calcium-channel blockers are developed with greater vasoselectivity, less negative inotropic effects, and reduced tendency to activate the renin-angiotensin system, their indications for use will continue to grow.

Angioplasty, Balloon, Coronary↗
PubMed1997

Changes in some psychophysiological parameters in speech information processing under masking noise effect.

The aim of the present work was to study the influence of masking broad-band (white), impulse and interrupted noise with intensities LAeq 60 and 90 dB(A) on the execution of some psychophysiological tasks. The following parameters were studied: pulse frequency and variation, breathing frequency and variation, vascular tone etc. The psychological tasks model different parts of the operators' activity and include: conduction of mathematical calculations at datum speed; test related to the information processing; complex optional task supplied by Piorkovski's device. After statistical processing of results by Student-Fischer's t test and monofactor dispersion analysis it was established that the masking noise effect was more strongly expressed in the execution of psychophysiological tasks connected with the main memory. Of all tested physiological parameters the changes in the peripheral circulation, expressed in elevated vascular tone of peripheral blood vessels, were the most significant.

Adult↗
PubMed1998

[Effect of ultrasound contrast medium in color Doppler of blood flow in transplant kidneys].

We have so far performed color Doppler echography to make diagnosis in renal transplantation. The ultrasound contrast agent in color Doppler developed and used recently has made possible the recording and measuring of low velocity wave in transplant kidneys. As characteristics of that, mention can be made of improvement in detection of the flow, reliability of assessment of the velocity, space resolving power. It is useful particularly for the peripheral blood vessels on chronic rejection and the interlobar artery on acute vascular rejection. With that put to practical use, imaging diagnosis in the field of renal transplantation has improved in its diagnosing ability and is expected to make further development in the future.

Contrast Media↗
PubMed1988

Calcitonin gene-related peptide acts as a novel vasodilator neurotransmitter in mesenteric resistance vessels of the rat.

Systemic blood pressure is controlled by changes in the resistance of the peripheral vascular bed for example in the mesenteric blood vessels. The tone of peripheral blood vessels is primarily maintained by sympathetic vasoconstrictor nerves. Although vasodilator innervation has been identified in certain isolated elastic arteries, it is not known whether vasodilator nerves contribute to the regulation of the peripheral resistance vessels. We present pharmacological evidence for the existence of nonadrenergic, noncholinergic (NANC) vasodilator nerves in the mesenteric resistance vessel of the rat and that the resistance is controlled by not only sympathetic vasoconstrictor nerves but also NANC vasodilator nerves. We also show that the neurogenic vasodilation was selectively abolished by depleting endogenous calcitonin gene-related peptide (CGRP), a potent vasodilator neuropeptide, from perivascular nerves. This indicates that CGRP is a novel vasodilator neurotransmitter and may play a role in control of the total peripheral resistance of systemic circulation through a local reflex mechanism.

Animals↗
PubMed1993

Magnetic resonance measurement of blood flow in peripheral vessels after acute exercise.

Velocity-encoded Cine magnetic resonance imaging (MRI) was used to measure blood flow in the anterior tibial artery (AT), posterior tibial artery (PT), and popliteal artery of adult human subjects (mean age 29 yr) before and after 90 s of ankle dorsiflexion exercise. Before exercise, mean flow, peak systolic velocity, and end-diastolic velocity in AT were 8.1 +/- 1.6 (SE, n = 6) ml/min, 26.9 +/- 2.6 cm/s, and -0.6 +/- 0.4 cm/s, respectively. After exercise, mean flow and peak systolic velocity in AT increased by 19-fold and 3-fold, respectively, and end-diastolic velocity increased to 8.7 +/- 1.1 cm/s. Flow in popliteal artery above its bifurcation was similar to the sum of flows in AT and PT, both before and after exercise. Flow in AT declined exponentially after exercise with a mean half-time of 4 min. The results demonstrate the utility of MR phase-encoded flow-velocity measurements for physiological studies of peripheral vascular dynamics after exercise.

Adult↗
PubMed1989

Physical properties of resistance vessel wall in peripheral blood flow regulation--I. Mathematical model.

A mathematical model is introduced to investigate the influence of the physical properties of the resistance vessel wall on the metabolic and myogenic mechanisms. The resistance vessel wall is assumed to have an elastic property and the elastic modulus to be a function of pressure (myogenic) and flow (metabolic). Blood is Poiseuille's flow. The resulting mathematical equations for pressure-flow, pressure-diameter, pressure-wall tension and pressure-wall elastic modulus relationships introduced obey Laplace's law. Poiseuille's law and Hooke's law. In comparison with the experimental data (pressure diameter), the mathematical model is confirmed to explain well the dynamic behavior of the resistance vessel wall in vivo.

Elasticity↗
PubMed1999

Estrogen protects peripheral and cerebral blood vessels from toxicity of Alzheimer peptide amyloid-beta and inflammatory reaction.

Due to increases in life expectancy, women are living 30 years or more beyond menopause. This has led to an increasing interest in the association between postmenopausal estrogen deficiency and degenerative diseases associated with aging such as cardiovascular disease, osteoporosis and dementia. Women are two times more likely to develop late-onset Alzheimer's disease (AD) than age-matched men. A large number of observational reports and a few randomized clinical trials have indicated that estrogen replacement therapy (ERT) may retard the development and severity of dementia in postmenopausal women. The mechanism underlying the protective action of estrogen in AD is under active investigation. A chronic inflammatory reaction mediated by abnormal deposition of proteins such as amyloid-beta (A beta) is central to the pathology of AD. We investigated the effect of low doses of conjugated estrogen (Premarin) in an animal model of A beta-induced vascular disruption and inflammatory reaction. This rodent model allows live videomicroscopic recording and electron microscopic analysis of peripheral vascular disruption and inflammatory reaction triggered by A beta. Estrogen prevented vascular deposition of A beta, endothelial and vessel wall disruption with plasma leakage, platelet and mast cell activation, and characteristic features of an inflammatory reaction: adhesion and transmigration of leukocytes. The beneficial effect was lost when estrogen treatment was discontinued. Estrogen also protected the cerebral blood vessels from endothelial dysfunction induced by A beta. This novel protective effect of estrogen against A beta cytotoxicity in peripheral and cerebral vasculature may contribute to the therapeutic efficacy of estrogen in AD and coronary vascular disease.

Aged↗
PubMed1984

The effects of carbon dioxide- and neodymium-YAG lasers on the central and peripheral nervous systems, and cerebral blood vessels.

The morphological reaction of brain and peripheral nerve tissue and of cerebral blood vessels to the application of two types of laser-beams is described. Lasers as cutting instruments produce smoother cut surfaces and provoke less bleeding than conventional techniques. There is almost no focal oedema. Their effects are limited to clearly determinable zones. Scar formation after laser cutting is minimised. With defocused laser-beams a photo-coagulation of tumours, for example, highly vascularised tumours or pituitary adenomas, is possible. Small arteries may be cut without bleeding. Peripheral nerves cut by use of lasers do not develop neuromas. The results of the laser technique are compared with those of conventional methods.

Animals↗