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At least 721 records · Page 40Linked to original sources
PubMedDate not supplied

[Quantitative patterns in the clinical manifestations of radiation sickness in large laboratory animals exposed to radiation at superlethal doses. Changes in the regulation of cardiovascular system function].

Dog exposure to doses from 39 to 124 Gy results in an increase of heart rate and tension in control of the cardiac rhythm, the extent being dose dependent. An additional physical load on the cardiovascular animals system reveals a high functional control reserves of the cardiovascular system which provides stable functioning even after exposure to the above doses.

Animals↗
PubMedDate not supplied

[The regulatory effects of opioid peptides--enkephalins--in controlling the activities of the cardiovascular system].

In this review we analyse the experimental and clinical findings demonstrating important regulatory significance of met-enkephalin, leu-enkephalin and their derivatives in the control of cardiovascular system activity. Enkephalin-positive immunoreactivity is revealed in the heart of different species of animals, and their cardiovascular effects are established in numerous investigations. It is determined that cardiac effects of enkephalins are essentially associated with modulatory influence at the presynaptic and postsynaptic levels on the activity of extracardiac neural regulation. Cardiovascular effects of endogenous opioid system are extremely important in developing of myocardial ischemia, cardiac arrhythmias and congestive heart failure. The cellular mechanisms of opioid effects are associated with stimulation of mu- and delta-subtypes of opiate receptors which stimulation of mu- and delta-subtypes of opiate receptors which are coupled with conductivity of ion channels, adenylate cyclase activity, phosphoinositide turnover and calcium-calmodulin-dependent protein kynases.

Animals↗
PubMed1985

Connections of neurons in the region of the nucleus tractus solitarius with the hypothalamic paraventricular nucleus: their possible involvement in neural control of the cardiovascular system in rats.

Extracellular recordings were made from 607 spontaneously firing neurons within the nucleus tractus solitarius (NTS) and its vicinity in urethane-anesthetized male rats. Following electrical stimulation of the hypothalamic paraventricular nucleus (PVN) area, 21% of the neurons were orthodromically excited, 6% were inhibited and 2.5% were antidromically activated. The antidromic spike latencies were 22-64 ms. Among those orthodromically responding neurons, 81 neurons were tested by pressure pulse stimulation of the isolated carotid sinus. The pressure stimulation produced excitation in 7 and inhibition in 13 neurons. Of the 8 tested neurons which were antidromically activated, one neuron was excited and another neuron inhibited by the pressure pulse stimulation. These results provide electrophysiological evidence for reciprocal connections between neurons in the NTS region and the PVN, and give support to the hypothesis that the PVN is involved in the neural control of the cardiovascular system.

Animals↗
PubMed1995

Beta 3-adrenoceptors in the cardiovascular system.

Behind the classic beta 1 and beta 2-adrenoceptors, recent molecular and pharmacological studies have described a new receptor, called the beta 3-adrenoceptor, in various mammalian tissues (brown and white adipose tissue, digestive smooth muscle). Few authors have investigated the putative existence of the beta 3-adrenoceptor in the cardiovascular system. This paper reviews the available data. In vitro studies show that beta 3-adrenoceptor agonists (BRL 37344, CGP 12177) induce a relaxation of fragments of rat carotid artery which is not antagonized by propranolol. In dogs, these drugs elicit a decrease in blood pressure due to peripheral vasodilation and an increase in heart rate which is of baroreflex origin. The vasodilating effects are mainly observed in cutaneous and adipose tissue vessels and cannot be explained by any known transductional mechanism. Activation of this vascular beta 3-adrenoceptor requires higher doses of catecholamines than for beta 1- or beta 2-adrenoceptors. In humans, the cardiovascular effects of beta 3-adrenoceptor agonists are explained by the activation of beta 1- or beta 2 (and not beta 3-)-adrenoceptors. These studies suggest the presence of vascular (but not cardiac) beta 3-adrenoceptors in dogs. In other species, including man, the presence of such cardiac beta 3-adrenoceptors remains to be resolved. Their physiological relevance remains unknown.

Adrenergic beta-Agonists↗
PubMed1988

Involvement of endogenous thyrotropin-releasing hormone in central regulation of the cardiovascular system after bleeding in conscious rats.

The 4th ventricle of a conscious rat was perfused using a push-pull cannula. The concentration of thyrotropin-releasing hormone (TRH) in the perfusate was significantly increased after withdrawal of 30% of the total blood. Administration of antiserum of TRH into the ventricle potentiated and prolonged the hypotension induced by the bleeding. These results suggest that endogenous brain TRH is involved in the central regulation of the cardiovascular system after bleeding in conscious rats.

Animals↗
PubMed2005

Effects of androgens on the cardiovascular system.

The evidence that men have a greater incidence of coronary artery disease than women of similar age, together with the fact that android fat distribution is associated with a greater incidence of coronary heart disease, have suggested that high testosterone levels are associated with an increased risk for coronary artery disease. The possible causal role of androgens in the development of cardiovascular disease has not been proven and, to date, there are no epidemiological and pathophysiological evidences to support that an hyper-androgenic state or androgen replacement is associated with cardiovascular disease in both sexes. Clinical studies have suggested that physiological testosterone supplementation in ageing males has a positive effect upon lipid profile. Additional potential protective cardiovascular effects of androgens may be related to their effect upon endothelial function and vasomotor tone. Few data are currently available on the correlation between plasma testosterone levels and coronary artery disease in men. Cross-sectional studies reported either reduced or similar plasma testosterone levels and/or androgens in patients with coronary artery disease as compared to controls without cardiovascular symptoms. Epidemiological studies addressing the importance of androgen levels upon cardiovascular mortality and morbidity have gathered inconclusive results. Prospective studies found no significant association between plasma testosterone and cardiac events in both sexes, while most cross-sectional studies have repetitively found an association between hypotestosteronemia and cardiovascular morbidity. In conclusion, androgens in general and testosterone in particular may have some protective effects on the cardiovascular system through their metabolic and direct effects upon human vasculature.

Aged↗
PubMed1989

Beat-to-beat regulation of left ventricular function in the intact cardiovascular system.

A variety of regulatory mechanisms have evolved to control the heart's pump function because the cardiovascular system must continually adapt to the changing demands that body functions place on it. This regulation takes place through many physiological systems; however, fine adjustments in cardiac pumping probably require adaptations more quickly than external control mechanisms (such as the autonomic nervous system) can compensate. Thus cardiac pumping is also regulated by mechanisms intrinsic to the heart. To better understand these intrinsic control mechanisms, we studied the beat-to-beat response of left ventricular function to continually varying changes in loading conditions produced by transiently occluding the pulmonary artery, venae cavae, and aorta. We used multiple linear regression to identify and quantify the important beat-to-beat determinants of left ventricular systolic function, quantified as stroke work. We could not adequately explain or predict beat-to-beat changes in stroke work with traditional determinants of ventricular function, preload, afterload, and heart rate, because a large systematic error remains after taking these traditional determinants of function into account. To eliminate this systematic error, we had to include some function of previous beat stroke volume and end-systolic size and pressure. This additional information significantly improved both our ability to model the observed transient changes in left ventricular stroke work and to predict additional observations that were not used to develop our model. We conclude that previous beat contraction history is an important determinant of left ventricular function and implies an important regulatory mechanism whereby the left ventricle can fine tune its function from beat to beat in response to continually changing loading conditions.

Animals↗
PubMed2002

[Functional state of the cardiovascular system of cosmonauts at rest in long-term space flight].

Analyzed were data of investigation of a group of cosmonauts who participated in long-term Mir missions (125 to 438 days). The scope of investigations made in resting cosmonauts (279 before and 234 in flight) allowed classification of the cardiovascular system functioning in three types depending on the cardiac index. Correlation between circulation type and genetic factors, age and conditions of investigations (at rest or prior to a functional test) has been established. In flight, most often the cosmonauts pointed to intensification of the chronotropic function of the heart, increase in minute volume, rises in the end-systolic blood pressure (BPes) and systolic pressure in the pulmonary artery, hyperkinetic circulation, particularly before functional testing. However, values of the parameters under study did not leave the borderlines of the physiological and, as a rule, age norms. An in-depth analysis revealed three types of reaction to microgravity. Increase in minute volume due to the stroke volume and heart rate was concurrent with the BPes rise. Diminution of the volumes of hemocirculation and development of eukinetic circulation were not found to significantly alter BPes. There were several cosmonauts who did not display any proved shifts in the parameters.

Adult↗
PubMed1997

Spinal anesthesia with clonidine and bupivacaine in young humans: interactions and effects on the cardiovascular system.

BACKGROUND: Clonidine, an alpha 2 agonist, is known to prolong the action of local anesthetics, and to provide a satisfactory analgesia; hypotension and bradycardia have been observed after its intrathecal administration. The aim of our study was to determine whether intrathecal administration of clonidine can reduce the dose of local anesthetic, and the effects of clonidine on the cardiovascular system, and on arousal level. METHODS: In a prospective, randomized study we evaluated 56 patients scheduled for minor surgical procedure (spermatic vein ligature) under unilateral spinal anesthesia with hyperbaric bupivacaine 1%. One half of patients received clonidine (105 micrograms) in addition to bupivacaine. Mean arterial pressure, heart rate were recorded baseline until 1 hour after surgery. Cardiac output, stroke volume, ejection fraction, systemic vascular resistance and left cardiac work were measured, by thoracic electric bioimpedance method, baseline until 1 hour after surgery. Sensory block, motor block and sedation level were measured at the beginning of anesthesia and for 6 hours after the end of surgery. RESULTS: In the clonidine treated group we did not observe variations of cardiovascular parameters; in the same group we did observe sensory block and motor block significantly prolonged, a higher sedation level and a significant postoperative analgesia. CONCLUSIONS: In summary, the addition of clonidine to hyperbaric bupivacaine seems to be particularly useful in unilateral spinal anesthesia, exerting minimal influence on haemodynamic parameters, and guaranting a satisfactory postoperative analgesia.

Adrenergic alpha-Agonists↗
PubMed1987

Structural adaptation of the cardiovascular system in hypertension. Hemodynamic consequences of vascular wall hypertrophy.

The existence of a structural adaptation of the cardiovascular system in hypertension has been known for many years, in fact already since the time of Bright. This paper is concerned with the hemodynamic consequences of the wall thickening of the small arteries and the arterioles. Studies are reported which illustrate the hemodynamic effects of the vascular changes in man, the limited reversibility of these changes and the early occurrence of the wall changes in the course of human hypertension. The pathophysiological role of the structural vascular changes in human hypertension is discussed.

Antihypertensive Agents↗
PubMed1991

[Evaluation of compensatory possibilities of the cardiovascular system in patients before reconstructive operations on the aorta and major arteries].

To determine functional reserves of cardiovascular system, two procedures were comparatively studied in evaluation of central hemodynamics: tetrapolar chest rheography under isovolemic loading and rheopolyglucin test. Close correlation registered in results of the tests allowed the authors to employ subsequently the isovolemic test alone. The patients with circulatory subcompensation and decompensation received 7-14-day preoperative cardiostimulation.

Aortic Diseases↗
PubMed1984

The effects of insulin on the cardiovascular system in patients with coronary heart disease.

In order to clarify the effects of insulin on the cardiovascular system in patients with and without coronary heart disease (CHD), we studied the changes of electrocardiogram (ECG), blood pressure, pulse rate, along with those of blood glucose, free fatty acid, immunoreactive insulin, cortisol and potassium during insulin tolerance test (ITT). The presence or absence of CHD was verified by the coronary angiography and various stress testings beforehand. In patients with CHD, ischemic ST-T wave changes were recorded following the increment of double product after insulin injection and these changes were quite similar to those recorded during exercise test. In patients without CHD, although hypoglycemia and suppression of lipolysis were achieved, ischemic ST-T wave changes were not recorded after insulin injection. Furthermore, in a patient with Triple Vessel Disease, ischemic changes of ECG provoked by ITT were abolished completely by the administration of nifedipine and propranolol. ITT may induce ischemic changes of ECG in patients with CHD by different mechanisms from those of exercise tests and it may provide a useful tool for the diagnosis of CHD in clinical applications.

Aged↗
PubMed1996

Direct measurement of nitric oxide in the cardiovascular system.

Nitric oxide generated from L-arginine is a messenger for cell-to-cell communication. Abnormalities in nitric oxide release have been implicated in diseases ranging from hypertension and atherosclerosis to septic shock and rheumatoid arthritis. We report here the in vivo and in vitro measurements of nitric oxide in the cardiovascular system using a porphyrinic sensor specific for NO. The sensor has a detection limit 10(-9) M, response time of 0.1-10 ms and diameter of 1-20 microns. Protected by an intravenous catheter or Swan-Ganz catheter, the sensor can be implanted into tissues as well as into the blood stream. Nitric oxide concentrations were measured directly in the heart and also in veins and arteries, ranging in diameter from 100 microns to 5 mm. Nitric oxide production was induced by the action of different physical agents (shear stress, stretching) as well as various chemical substances agonists (bradykinin, acetylcholine, ATP).

Animals↗
PubMed1989

[Effect of transportation noise on the status of the cardiovascular system of the population].

The results of a multipronged study of noise effect on the state of the cardiovascular system of the urban population are presented. The study of regular noise effect on various population groups has been conducted under natural and laboratory conditions. A complex of appropriate investigation techniques has been used. The population of noise-exposed regions has higher rates and more distinct forms of disorders in myocardium, vessel elasticity, hemodynamics, extracardial regulation and higher risk of cardiovascular disease than those living under more quiet conditions.

Adult↗