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At least 613 records · Page 34Linked to original sources
PubMed1979

Plastic casts of embryonic respiratory and cardiovascular system: a technique.

This report describes a technique for producing plastic casts of the cardiovascular and respiratory systems of the chick embryo at Stage 36 or older. For casts of the cardiovascular system, polymerization compound is injected in the right ventricle filling the heart, venous, and arterial system. A two stage injection produced more detailed casts of the pulmonary vasculature. For respiratory system casts, the compound is injected in the trachea filling the bronchi and air sacs. Casts are prepared by tissue corrosion in 10% potassium hydroxide. This technique is an alternative to serial section reconstruction in the study of developing cardiovascular and respiratory system.

Animals↗
PubMed1993

A comparison of overall mathematical models of the cardiovascular system for simulating response to orthostatic stresses.

Although numerous mathematical models of the cardiovascular system (CVS) have appeared in the literature only a few of them are models of the entire system with detailed representation of the heart, the vasculature, and the control elements. Like all models of biological systems, these models vary in complexity, and most of them are stimulus- specific. Their ability to simulate with acceptable accuracy either responses over a wide range of the stimulus or responses to stimuli of similar kind has not been reported. In this paper, three mathematical models of the CVS are examined in terms of their response to different orthostatic stresses, namely, lower body negative pressure (LBNP), head-up tilt, and blood loss. The short-term orthostatic responses of the models are compared to available experimental data. The models are: (i) Croston and Fitzjerrell's for study of LBNP and head-up tilt response, (ii) Jaron et al.'s for study of +Gz response, and (iii) Pullen's for simulation of response to blood loss. We will henceforth refer to these models by the letters C, J, and P, respectively.

Hemorrhage↗
PubMed2006

Spontaneous lesions of the cardiovascular system in purpose-bred laboratory nonhuman primates.

This retrospective study was performed to determine the range, occurrence and incidence of spontaneously arising histopathological findings of the cardiovascular system in purpose-bred laboratory nonhuman primates. Data were collected from 84 controlled toxicological studies with equal numbers of male and female animals and full tissue lists. Attempts were also made to standardize pathological terms used by various original pathologists. Tissue sections from 2464 animals, which included 2050 cynomolgus monkeys (Macaca fascicularis), 284 common marmosets (Callithrix jacchus) and 130 rhesus monkeys (Macaca mulatta) were examined. The most common cardiac finding was focal myocardial inflammation, subcategorized as either "inflammatory cell infiltration" (339) or "focal myocarditis" (131). Other cardiac findings included mineralization (29), endocarditis (16), pericarditis (10), squamous cysts (6) and ectopic thyroid tissue (5). Perivasculitis/vasculitis in the kidney, lung, meninges, sciatic nerve, and other tissues (206) was the most common vascular lesion. Focal myocarditis was more common in male (60%) than female (40%) animals. Cardiac mineralization and extramedullary hematopoiesis were more common in marmosets than other species while ectopic thyroid tissue was present in marmosets and cynomolgus monkeys. To our knowledge, this is the first study to demonstrate the range and incidence of spontaneous cardiovascular lesions in laboratory nonhuman primates.

Animals↗
PubMed1990

[Pharmacological studies of celiprolol: III. Effects of celiprolol on the cardiovascular system and renal function, and its antiarrhythmic effects].

Effects of celiprolol on the cardiovascular system and renal function, and its antiarrhythmic effects were studied. 1. In anesthetized dogs, celiprolol (0.01-3 mg/kg, i.v.) dose-dependently depressed the maximum rate of rise of left ventricular pressure, cardiac output and cardiac work less severely than propranolol and atenolol. 2. Celiprolol (0.01 mg/kg, i.v.) decreased the myocardial oxygen consumption in anesthetized dogs as potently as propranolol. 3. Celiprolol (0.03-3 mg/kg, i.v.) tended to increase femoral blood flow. Celiprolol (1 mg/kg, i.v.) increased common carotid blood flow. 4. Celiprolol decreased urine volume and urinary excretion of Na+ and Cl- at doses of 1 and 10 mg/kg and increased the sodium reabsorption rate at a dose of 10 mg/kg in anesthetized dogs, whereas it produced no change in plasma renin activity. 5. Celiprolol inhibited both halothane-adrenaline arrhythmia in dogs and ouabain-induced arrhythmia in rabbits. Its antiarrhythmic effects were 1/10-1/3 as potent as those of propranolol. 6. Celiprolol suppressed the maximum rate of rise of action potential at a concentration of 3 x 10(-4) M, which was 30 times as high as that of propranolol. Celiprolol (3 x 10(-5)-3 x 10(-4) M) dose-dependently shortened the effective refractory period (ERP), but it produced no change in the ratio of ERP to action potential duration. 7. These results suggest that celiprolol may be a useful drug for the treatment of ischemic heart disease and some types of arrhythmia, and that it has only a little influence on renal function.

Action Potentials↗
PubMed1982

[A study of three potential antidepressants (amineptin, mianserin and nomifensin) on the cardiovascular system and isolated intestine (author's transl)].

We studied the effects on the cardiovascular system and isolated intestine of three potential antidepressants : amineptin, nomifensin and mianserin. 1) No animals died in spite of doses well above the therapeutic range, evidencing the good tolerance of the compounds. 2) Effects on heart rate were variable; the only significant effect was cardioacceleration seen with mianserin in doses above 5 mg/kg. 3) The only significant effect on the auriculoventricular refractory period was recorded with mianserin. 4) Amineptin was the only compound that increased blood pressure. 5) Auriculoventricular conduction was slowed with mianserin in doses above 10 mg/kg. 6) On isolated rat duodenum, mianserin was spasmogenic in concentrations above 100 microgram/100 ml. 7) in comparison to tricyclic antidepressants, these three compounds carry only few risks of adverse side-effects.

Animals↗
PubMed1999

Cell cycle regulatory molecules (cyclins, cyclin-dependent kinases and cyclin-dependent kinase inhibitors) and the cardiovascular system; potential targets for therapy?

In the preceding sections we have described the potential for using cell cycle regulatory molecules as targets for drug development within the cardiovascular system. Opportunities for affecting the expression and activities of selected cell cycle regulatory molecules exist in interventional cardiological procedures such as PTCA to limit specifically the intimal hyperplasia of vascular smooth muscle cells that occurs following angioplasty. In addition, the potential for targeting the cardiac myocyte cell cycle to re-initiate cell division in a controlled manner would provide a suitable approach for repairing damaged areas of myocardial tissue following an infarct. Although this approach has not been demonstrated to date in vivo, data from transgenic mouse models and in vitro studies have implicated the cell cycle as a suitable target for manipulation. The next few years will enable the feasibility of this approach to be demonstrated.

Animals↗
PubMed2005

A bond graph model of the cardiovascular system.

The study of the autonomic nervous system (ANS) function has shown to provide useful indicators for risk stratification and early detection on a variety of cardiovascular pathologies. However, data gathered during different tests of the ANS are difficult to analyse, mainly due to the complex mechanisms involved in the autonomic regulation of the cardiovascular system (CVS). Although model-based analysis of ANS data has been already proposed as a way to cope with this complexity, only a few models coupling the main elements involved have been presented in the literature. In this paper, a new model of the CVS, representing the ventricles, the circulatory system and the regulation of the CVS activity by the ANS, is presented. The models of the vascular system and the ventricular activity have been developed using the Bond Graph formalism, as it proposes a unified representation for all energetic domains, facilitating the integration of mechanic and hydraulic phenomena. In order to take into account the electro-mechanical behaviour of both ventricles, an electrophysiologic model of the cardiac action potential, represented by a set of ordinary differential equations, has been integrated. The short-term ANS regulation of heart rate, cardiac contractility and peripheral vasoconstriction is represented by means of continuous transfer functions. These models, represented in different continuous formalisms, are coupled by using a multi-formalism simulation library. Results are presented for two different autonomic tests, namely the Tilt Test and the Valsalva Manoeuvre, by comparing real and simulated signals.

Cardiovascular System↗
PubMed1988

Hypothalamic GABA suppresses sympathetic outflow to the cardiovascular system.

We studied the cardiovascular effects of altering GABA-ergic tone in the posterior hypothalamus in rats. Animals were equipped with chronic guide cannulas placed in the posterior hypothalamus, arterial and venous catheters, and a bipolar electrode on the splanchnic nerve. Microinjected bilaterally into the posterior hypothalamus in conscious rats, the postsynaptic gamma-aminobutyric acid (GABA) antagonists bicuculline methiodide and picrotoxin rapidly increased heart rate, blood pressure, and sympathetic nerve activity. Microinjection of the GABA agonist muscimol into this same region decreased heart rate, blood pressure, and sympathetic nerve activity in conscious rats. In contrast, muscimol infused into the posterior hypothalamus of anesthetized rats failed to alter heart rate or blood pressure. We conclude that 1) the posterior hypothalamus contains a sympathoexcitatory system that is modulated by changes in GABA-ergic tone and 2) tonic GABA-ergic inhibition is sufficient to completely suppress the activity of this hypothalamic sympathoexcitatory system in anesthetized animals but not in conscious rats.

Animals↗
PubMed2006

[Effects of vitamin D on the cardiovascular system].

Active vitamin D plays important roles not only in bone and mineral metabolism but also in the cardiovascular system. Cohort studies in hemodialysis patients demonstrated that use of active vitamin D analogs was associated with reduced risk of death, particularly death from cardiovascular disease. Treatment with vitamin D had beneficial effects on cardiac and immune functions in dialysis patients, and inflammatory markers in non-renal subjects. Also, anti-proteinuric effect was recently shown in chronic kidney disease. Experimentally, active vitamin D inhibits atherogenic cellular behaviors and activation of the renin-angiotensin system. Thus, active vitamin D is a regulator of cardiovascular and kidney functions.

Animals↗
PubMed1998

Transfer and expression of recombinant nitric oxide synthase genes in the cardiovascular system.

Gene therapy involves the transfer of a functional gene into host cells to correct the malfunction of a specific gene or to alleviate the symptoms of a disease. For gene transfer to the cardiovascular system, adenoviral vectors are the most efficient means of transfer. Recently, transfer and functional expression of recombinant nitrio oxide synthase (NOS) genes to cerebral and cardiovascular beds have been demonstrated both ex vivo and in vivo. Here, Alex Chen and colleagues review current progress in the field of vascular NOS gene transfer and the potential use of NOS gene therapy for a number of cardiovascular diseases. Although the feasibility of the NOS gene transfer approach has been demonstrated in animal models, currently available vectors have a number of technical and safety limitations that have to be solved before human NOS gene therapy for cardiovascular disease can be attempted.

Animals↗