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At least 541 records · Page 30Linked to original sources
PubMed1987

Tissue perfusion during normovolemic hemodilution investigated by a hydraulic model of the cardiovascular system.

Normovolemic hemodilution on a whole body basis is studied by means of a steady flow, hydraulic analogue simulation of the cardiovascular system, based on the Casson's model and current hemodynamic and rheological data. The vasculature is divided into serially connected compartments whose hydraulic resistance is characterized by the average diameter, length, number of vessels, and the corresponding rheological properties of blood formulated by Dintenfass (1971) and Lipowsky et al. (1980). This model computes the pressure distributions in all compartments, where the calculated venous pressure modulates the cardiac function according to the Starling mechanism for cardiac performance. The alterations of flow induced by the action of the heart are added to the effects due to changes in peripheral vascular resistance as a result of hematocrit variation. This model shows that when the response of heart to the changes of venous pressure is impaired, the maximum oxygen carrying capacity occurs at 40% hematocrit (H) where it is 1% higher than normal hematocrit (H = 44%). The normal cardiac response to the changes of venous pressure, causes the maximum oxygen carrying capacity to occur at 32% H where it is 12% greater than that at normal hematocrit. Mean arteriolar pressure and capillary pressure increase while venular pressure is slightly reduced during normovolemic hemodilution.

Blood Pressure↗
PubMed1983

Impaired autonomic responsiveness of the cardiovascular system of the rat induced by a heat-labile component of Bordetella pertussis vaccine.

Bordetella pertussis vaccination induces severe impairment of the autonomic responsiveness of the cardiovascular system in rats. The vasodilation after beta 2-adrenoceptor stimulation with salbutamol as well as the negative chronotropic action induced by the muscarinic receptor stimulant arecoline were inhibited 4 days after vaccination. Moreover, basal blood pressure values appeared to be significantly lower in B. pertussis-vaccinated rats compared with control animals. These effects were dependent upon the bacterial strain used. Differences in pharmacological activity due to strain differences paralleled variations in the content of lymphocytosis-promoting factor of the vaccine. The inhibitory effects were absent after the administration of vaccine heated for 1 h at 80 degrees C, implicating an important role for a heat-labile component, e.g., lymphocytosis-promoting factor, and not for a heat-stable constituent, e.g., endotoxin (lipopolysaccharide). Previous studies indicate that some early biological effects elicited by B. pertussis vaccine can be attributed to lipopolysaccharide, whereas late induced effects are mainly brought about by lymphocytosis-promoting factor. For that reason a role for lipopolysaccharide might be excluded because 5 h after vaccination no disturbances of the autonomic nervous system were observed. We conclude that B. pertussis vaccination induces autonomic hyporesponsiveness due to a heat-labile component that is assumed to be lymphocytosis-promoting factor.

Albuterol↗
PubMed1988

[Functional status of the cardiovascular system in Hodgkin's disease and the effect of radiotherapy].

The main indices of cardiohemodynamics, phase structure of the cardiac cycle and ECG were studied in 34 patients with Hodgkin's disease aged 16 to 43: before the initiation of therapy, after a course of radiotherapy and in long term after therapy. The patients were characterized by tachycardia increasing with a degree of a process, ECG signs of myocardiodystrophy, a tendency to the formation of the phase syndrome of hypodynamia, slight pulmonary hypertension, a decrease in AP and peripheral vascular resistance. After a course of radiotherapy according to a radical program functional indices of the cardiovascular system in most of the patients returned to normal. However signs of radiation pericarditis with a favorable clinical course developed in some patients. Long after therapy positive changes in the cardiovascular system were noted among patients with IIA stage, negative shifts were noted in patients with III-IV stage.

Adolescent↗
PubMed1993

Connexin expression in the developing avian cardiovascular system.

Recent observations have suggested that the patterns of expression of the gap junction protein connexin43 in the developing cardiovascular system of the avian embryo diverge significantly from the patterns previously seen in mammalian species. Therefore, a detailed analysis of connexin43 expression in the chicken embryo was performed by use of immunofluorescent localization with two different connexin43-specific antipeptide antibodies as well as Western and Northern blot analysis. Connexin43 protein was not detected in the avian myocardium, the venous system, or the smaller vessels of the arterial system. Rather, it was limited exclusively to the vessels of the arterial outflow tract in a concentric pattern that became evident by embryonic day 8. Double staining with anti-alpha-smooth muscle actin and connexin43 demonstrated colocalization in the media of outflow tract vessel walls. The developmental expression of connexin43 was found to mirror the spatial patterning of secondary actin; connexin43, however, preceded the expression of secondary actin by a period of 1-2 days. In contrast, antibodies to a related gap junction protein (connexin42) revealed an absence of immunostaining in the avian outflow tract. Double staining with anti-connexin42 and anti-A-cell adhesion molecule (specific for avian intercalated discs) demonstrated colocalization between cardiac myocytes, indicating that connexin42 is a constituent of avian myocardial gap junctions. In light of these findings, developmental expression of differing myocardial connexins may reconcile previous studies showing different physiological properties of avian and mammalian cardiac gap junctions.

Animals↗
PubMed1984

Pharmacological studies of mabuterol, a new selective beta 2-stimulant. II: Effects on the cardiovascular system and smooth muscle organs.

Effects of dl-1-(4-amino-3-chloro-5-trifluorome-thyl-phenyl)-2-tert.-bu tylamino-ethanol hydrochloride (mabuterol) on the cardiovascular system and smooth muscle organs were investigated in comparison with those of isoprenaline (isoproterenol), salbutamol and procaterol, and the following results were obtained. Mabuterol (i.v.) produced a dose-dependent decrease in the blood pressure at doses ranging from 0.3-1000 micrograms/kg, and the heart rate was slightly increased at 0.3-30 micrograms/kg but decreased at 100-1000 micrograms/kg in rats, cats and dogs. The effects of mabuterol on the blood pressure, total peripheral vascular resistance (TPR) and heart rate were respectively 14, 37 and 104 times less potent than those of isoprenaline and there were none on the maximum dp/dt in the left ventricle in cats. In dogs, mabuterol had 356 and 118 times less effect on the blood pressure and TPR than isoprenaline and slightly increased the heart rate and maximum dp/dt. Mabuterol (p.o.) decreased the blood pressure at doses ranging from 3 micrograms-100 mg/kg, and the heart rate was increased at 3 micrograms-10 mg/kg, but decreased at 100 mg/kg in conscious and anesthetized rats. In the guinea pig atria, mabuterol slightly increased the heart rate and contractile force, but in the electrically driven left atrium mabuterol had no effect whereas procaterol slightly increased the contractile force. Mabuterol inhibited the positive inotropic effect of isoprenaline at 10(-7) g/ml and decreased the maximum driving frequency at 3 X 10(-6) g/ml. Mabuterol was 3 times more potent in relaxing the isolated rat uterus, but 700 times less potent than isoprenaline in relaxing the rabbit jejunum. Mabuterol (p.o.) depressed the intestinal propulsion and was equipotent to isoprenaline and 2.5 times less potent than salbutamol. Mabuterol had no effect on alpha-adrenergic, acetylcholine and histamine receptors. These results suggest that mabuterol has a specific effect on beta 2-adrenoceptors with no beta 1-stimulation. In addition, mabuterol exhibited beta 1-blocking activity at dosages 200-300 times higher.

Adrenergic beta-Agonists↗
PubMed1992

Mathematical modelling of flow distribution in the human cardiovascular system.

The paper presents a detailed model of the entire human cardiovascular system which aims to study the changes in flow distribution caused by external stimuli, changes in internal parameters, or other factors. The arterial-venous network is represented by 325 interconnected elastic segments. The mathematical description of each segment is based on equations of hydrodynamics and those of stress/strain relationships in elastic materials. Appropriate input functions provide for the pumping of blood by the heart through the system. The analysis employs the finite-element technique which can accommodate any prescribed boundary conditions. Values of model parameters are from available data on physical and rheological properties of blood and blood vessels. As a representative example, simulation results on changes in flow distribution with changes in the elastic properties of blood vessels are discussed. They indicate that the errors in the calculated overall flow rates are not significant even in the extreme case of arteries and veins behaving as rigid tubes.

Blood Flow Velocity↗
PubMed2002

Nitric oxide transport and storage in the cardiovascular system.

Despite short halflife in biological fluids, nitric oxide (NO) can produce remote or long lasting effect in the cardiovascular system. Long distance transport or local storage of NO might explain these effects. In blood, recent findings suggest that in addition to being a major consumption pathway, interaction of NO with hemoglobin may permit O(2)-governed transport of NO (as S-nitrosohemoglobin) to tissues in which NO may be released together with O(2), via transnitrosation of a transport protein. In blood vessels, two different putative NO stores have been characterized. The first is the photosensitive store, formed from endothelium-derived NO. The mechanism of NO release from this store in the body (in absence of light) and its physiological relevance are unknown. The second store is generated in conditions of high tissue NO levels, as a consequence of the inducible NO synthase activity or in various stress conditions. This NO store involves formation of protein-bound dinitrosyl iron complexes or S-nitrosated proteins, or both. Low molecular weight thiols can displace NO from these stores and probably transfer it to target membrane protein(s) such as K(+) channels, via transnitrosation reactions. These stores may be involved in defence mechanisms against inflammation or stress. Thus, NO transport and storage mechanisms may be implicated in a variety of NO effects. The mechanisms of their formation and of NO release and their physiologic and pathophysiologic relevance deserve further investigations.

Animals↗
PubMed2002

[Effects of physical training and age-induced structural and functional changes in cardiovascular system and skeletal muscles].

Age-related morphological changes in the cardiovascular system refer to a thickening of the arterial wall as well as a diffuse increase in the wall thickness of the myocardium. In terms of function, this leads to a decrease of the myocardial contractility in systole and to a delay of the diastolic myocardial relaxation. At the arterial wall, an impairment of wall elasticity as well as a decrease of the vasoreagibility can be observed. The systolic blood pressure and the blood pressure amplitude rise; the blood flow-dependent vasodilatation mediated by endothelial cells decreases. The loss of cardiac pacemaker cells by approximately 90% from the 2nd to the 8th decade leads to a reduction of the heart rate variability and to a decrease of the maximum heart rate during exhaustive physical exercise. Hemodynamically these changes resulted in a continuous decline of the maximum cardiac output as well as the maximum oxygen transport capacity. Between the 3rd and 8th decade the peripheral skeletal muscle mass decreases as a result of a reduction of the size and the number of muscle fibers with an overproportional loss of 30-40% regarding the highly glycolytic type IIb fibers. Furthermore, the intramuscular capillarization declines so that, with a concomitant decrease in the number and size of the mitochondria, the supply with oxygen and energy sources and consecutively the aerobic muscular energy metabolism decreases by 8-10% per decade beginning with the 4th to 5th decade. Additionally, the maximum and explosive muscular strength decreases by 30-35% from the 4th decade onwards. In older, healthy men who perform a regular aerobic muscular training in endurance sport disciplines (e.g., walking, jogging or cycling), a decrease of the resting heart rate, a restoration of the primarily lowered heart rate variability, an improvement of the early diastolic left-ventricular filling as well as a significant increase in the VO2max could be proven. Other studies showed that regular endurance training on a cycle-ergometer resulted in a significant increase in capillarization within the exercising muscle groups. In older, trained individuals a reduced stiffness of the arterial vessel walls and an improved maximum exercise-induced muscular blood supply occurs. In other training studies performed with older subjects, a positive influence of regular endurance training on the carbohydrate metabolism along with an improvement of the primarily reduced insulin sensitivity could be demonstrated. In older men and women who regularly underwent muscular strength training, a significant increase in maximum strength with a significant increase in the proportion of type II muscle fibers was found.

Adult↗
PubMed1999

Retinoids and cell growth in the cardiovascular system.

Deficiency of vitamin A and its retinoid metabolites has been associated with a number of developmental abnormalities in the cardiovascular system. Many of these effects are mimicked by targeted deletion of retinoic acid receptors in the embryo. Retinoids also display anti-growth activity in fully differentiated cardiac and vascular cells. These activities together with favorable effects on the clotting mechanism suggest that retinoids may prove useful in the management of hypertrophic/hyperproliferative disorders of the heart and vascular wall.

Animals↗
PubMed1981

The effects of chronic oral cimetidine therapy on the cardiovascular system in man.

1 The demonstration of histamine (H2) receptors in the cardiovascular system in man and the widespread use of the specific H2 receptor antagonist cimetidine for the treatment of peptic ulcer has necessitated assessment of the cardiovascular effects of this drug during oral therapy in man. 2 Consequently, nineteen patients with a history of peptic ulcer but in symptomatic remission underwent a double-blind crossover trial of oral cimetidine v placebo, each treatment period lasting 4 weeks. No significant difference in various cardiac parameters at rest (heart rate, blood pressure, ECG) or following a maximal treadmill exercise test (time-into-protocol, maximum heart rate and blood pressure) was found between the groups. Similarly, cimetidine produced no change in the incidence of ventricular ectopics or in heart rate on 24 h ambulatory monitoring and had no effect on left ventricular volume or contractility as measured by echocardiography. 3 Thus oral administration of cimetidine in a dose of 400 mg four times daily was associated with no demonstrable cardiovascular changes. In addition, since this dose is thought compatible with cardiovascular H2 receptor blockade this study favours the lack of a physiological role for these receptors in man.

Cardiovascular Diseases↗
PubMed1998

Xenopus eHAND: a marker for the developing cardiovascular system of the embryo that is regulated by bone morphogenetic proteins.

The bHLH protein eHAND is a sensitive marker for cardiovascular precursors in the Xenopus embryo. The earliest site of expression is a broad domain within the lateral plate mesoderm of the tailbud embryo. This domain comprises precursors that contribute to the posterior cardinal veins in later stages. Surprisingly, expression is profoundly asymmetric at this stage and is random with respect to embryo side. XeHAND is also expressed in an anterior domain that encompasses the prospective heart region. Within the myocardium and pericardium, transcripts are also asymmetrically distributed, but in these tissues they are localised in a left-sided manner. Later in development XeHAND transcripts are largely restricted to the ventral aorta, aortic arches and venous inflow tract (sinus venosus) which flank the heart itself, but no expression is detected in neural crest derivatives at any stage. This demonstrates that patterns of XeHAND expression differ markedly amongst vertebrates and that in Xenopus, XeHAND expression identifies all of the earliest formed elements of the cardiovascular system. In animal cap explants, expression of XeHAND (but not other markers of cardiogenic differentiation) is strongly induced by ectopic expression of the TGFbeta family members, BMP-2 and BMP-4, but this can be blocked by coexpression of a dominant negative BMP receptor. This suggests that XeHAND expression in the embryo is regulated by the ventralising signals of bone morphogenetic proteins. High levels of expression are also detected in explants treated with high doses of activin A which induces cardiac muscle differentiation. No such effect is seen with lower doses of activin, indicating that a second pathway may regulate the XeHAND gene during cardiogenesis.

Amino Acid Sequence↗
PubMed1975

Comparison of dopa decarboxylase inhibitor (carbidopa) combined with levodopa and levodopa alone on the cardiovascular system of patients with parkinson's disease.

The effects of carbidopa combined with levodopa (carbidopa/levodopa) and levodopa alone on the cardiovascular system of patients with Parkinson's disease were evaluated. Thirty-eight patients who had been on stable doses of levodopa underwent a complete cardiac examination, including measurement of recumbent and erect blood pressure and 24 hour ambulatory electrocardiographic monitoring. Patients were classified with respect to the presence or absence of clinically significant heart disease and ventricular arrhythmias. Nineteen of the 38 patients (50 percent) had heart disease, and 12 (32 percent) had significant ventricular arrhythmias. Eleven of the 12 with arrhythmias had underlying heart disease. The incidence of arrhythmias did not correlate with the dose of levodopa. The patients were subsequently randomly assigned to treatment groups receiving either carbidopa/levodopa or levodopa alone. There was no significant difference in the severity of ventricular arrhythmias or in the incidence of orthostatic hypotension in the group assigned to carbidopa/levodopa compared with the group receiving levodopa.

Adult↗
PubMed1991

Effects of pirarubicin, an antitumor antibiotic, on the cardiovascular system.

In the present study we examined the effects of pirarubicin [(2"R)-4'-O-tetrahydropyranyladriamycin, THP] on a cardiovascular system. An injection of THP (0.39-3.13 mg/kg, i.v.) reduced the mean blood pressure and caused an increase in the respiratory air rate in anesthetized rats. At 1.5 x 10(-6)-1.5 x 10(-5) M, THP markedly relaxed a contraction induced by 10(-7) M norepinephrine in rat aorta with endothelium but not in that without endothelium. At a dose of 0.02-0.5 mg, THP produced an increase in the contractile force and the perfusion flow of isolated perfused guinea pig hearts. At a higher concentration (4.5 x 10(-5)-1.5 x 10(-4) M), it produced a slight increase in the contractile force of the left atria in guinea pigs. This positive inotropic action of THP was inhibited by diphenhydramine (10(-6)-5 x 10(-5) M), chlorpheniramine (3 x 10(-7)-3 x 10(-5) M), and tripelennamine (3 x 10(-7)-3 x 10(-5) M) but not by propranolol (10(-6) M), cimetidine (10(-5) M), diltiazem (10(-6) M), or ryanodine (10(-8) M). THP given i.v. at 2.5 mg/kg elevated the plasma histamine level in anesthetized dogs. From these data, we conclude that THP mainly relaxed the rat aorta in the presence of endothelium and that at higher concentrations, it increased the contractile force in the cardiac muscle, probably mediated through the release of histamine.

Animals↗
PubMed2001

[Melatonin and the cardiovascular system].

In recent years, melatonin, the most prominent product of the pineal gland, has evoked considerable interest. In this report we reviewed the effects of melatonin on cardiovascular system.

Antioxidants↗
PubMed1998

[Congenital developmental defects of the cardiovascular system from the aspect of genetic factors and dysmorphogenesis].

Congenital defects of cardiovascular system have marked impact on the morbidity, invalidization and mortality of human population. Genetic factors are the most important factors in their etiology. The authors analyze the role of genetic factors and some problems of cardiovascular dysmorphogenesis important for evaluation of the reasons and risk of repeated congenital heart diseases family occurrence using clinical data and professional literature. (Tab. 7, Ref. 19.)

Abnormalities, Multiple↗