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At least 991 records · Page 55Linked to original sources
PubMed1995

Insulin-like growth factor I and its binding proteins in the cardiovascular system.

A large body of evidence has conclusively shown that IGF I is an essential regulator of developmental growth. Thus mice bearing a null mutation for the IGF IR gene invariably die shortly after birth, and mice bearing a null mutation for the IGF I gene have a high neonatal mortality rate and marked growth retardation [158,159]. The ubiquitous effects of IGF I make it likely that this autocrine/endocrine system plays an important role in cardiovascular development. Its potential role in cardiovascular pathophysiology has raised considerable interest over the last several years. There is strong evidence that IGF I is a critical determinant of vascular growth responses in vitro and in vivo. Regulation of VSMC IGF IR availability appears to be crucial for the control of VSMC growth, and as such is at a convergence point for the effects of multiple growth factors. Clinical studies relating to IGF I in hypertension are extremely limited but significant data from animal studies now suggest a role for IGF I as a mediator of hypertrophic/hyperplastic responses in hypertension. Furthermore, significant animal data now exist implicating IGF I as an important mediator of cardiac hypertrophic responses. The development of a specific pharmacologic inhibitor of the IGF IR should allow rational clinical trials to address the function of IGF I as a mediator of cardiovascular growth responses. Specifically, areas of great interest will include the potential prevention of post-angioplasty restenosis, of atherosclerotic lesion development and progression, and of the complications of hypertensive vascular disease. The use of IGF I to ameliorate myocardial growth and function post infarction, to promote angiogenesis and collateral artery formation in the setting of peripheral vascular disease, are other important directions for future research. The use of IGF I to improve wound healing, improve recovery from acute renal failure and improve glucose control is currently under investigation. Clearly ongoing studies addressing the mechanisms whereby IGF I interacts with its receptor and binding proteins to produce its effects in cardiovascular tissues, will provide a rationale for novel and pertinent clinical research.

Animals↗
PubMed1997

Effects of magnesium sulfate on the canine cardiovascular system complicating astemizole overdose.

Polymorphic ventricular arrhythmias induced by astemizole overdose have been reported to be successfully managed with intravenous magnesium sulfate. This study was designed to assess the effects of magnesium sulfate on the cardiovascular system, complicating astemizole overdose, the better to understand the therapeutic utility and undesirable effects of magnesium sulfate. Beagle dogs were anesthetized with halothane inhalation (n = 6). Monophasic action potential of the right ventricle, electrocardiogram, and systemic and left ventricular pressure were continuously monitored. Cardiac output was measured by a thermodilution method. Effective refractory period of the right ventricle was assessed by programmed electrical stimulation. An intentionally high dose of astemizole (3 mg/kg, i.v.) prolonged the repolarization and refractory period, while it decreased the sinus automaticity, ventricular contraction, and conduction. A canine antiarrhythmic dose of magnesium sulfate (100 mg/kg, i.v.) was additionally injected 1 h after i.v. astemizole. Magnesium sulfate increased the atrioventricular conduction time, electrical vulnerability, and preload of the left ventricle, while it decreased the blood pressure and cardiac output, besides the effects similar to those observed after i.v. astemizole. The plasma concentration of astemizole was at least 10 times higher than its therapeutic concentration during the experimental period. Magnesium sulfate could be expected to act as a calcium channel blocker during astemizole overdose; however, it may not antagonize the proarrhythmic effects of astemizole.

Animals↗
PubMed1982

[Changes in the cardiovascular system after continuous and intermittent administration of the rodenticide ratron].

The authors follow up the effect of "Ratron" a raticide (coumarin derivative) with two regimes of administration--monotonous and intermittent--upon the state of the cardiovascular system of experimental animals. The experiment was carried out on 65 female albino rats, grouped into three groups: group I--20 animals treated 5 times weekly with 1/100 LD50 ratron--five weeks; group II--25 animals, administered 5 times weekly every second week 1/50 LD50, and group III--20 controls. At the end of the sixth month, the state of the metabolic processes and the qualitative and quantitative characteristic of the connective tissue of myocardium and aorta were followed up by biochemical and histological methods. Unidirectional deviations in metabolism and the structure of myocardium and aorta were observed under the effect of both regimes, the changes being better manifested with the intermittent administration of ratron. Data were established not only about the general toxic effect of ratron but about the direct lesions of vessels, multiple hemorrhages, interstitial oedema, regeneration of endothelium, structural changes in the small vessels, changes in the components of the basic intercellular substance of the connective tissue.

Animals↗
PubMed1976

General pharmacological properties of a new non-opiate antitussive: zipeprol (3024 CERM). II. Actions on the cardiovascular system, intestinal transit and central nervous system.

The effects of 1-(2-methoxy-2-phenyl)-ethyl-4-(2-hydroxy-3-methoxy-3-phenyl)-propyl-piperazine-dihydrochloride (zipeprol, 3024 CERM, Respilene), a new nonopiate antitussive agent, have been studied on the cardiovascular system, intestinal function and the central nervous system. Most of these studies were performed comparatively with reference antitussives, particularly codeine, whose activites in these fields are the basis of its undesirable side effects. In the dog, zipeprol showed no hypotensive or cardiac-depressant activity. It did not alter pulmonary arterial pressure. An important antiarrhythmic action was apparent in studies on rhythm disturbances induced by ouabain and coronary ligation. Intestinal function, measured by the recording of peristaltic movements in the dog and the speed of intestinal transit in the rat, was not modified by the product. Zipeprol showed no characteristic action on the central nervous system. Analgesic activity was seen only at doses just below toxic levels. Finally in the rat and the mouse, no evidence of physical dependence was seen after prolonged treatment. This together with the absence of chemical similarity to the morphinics, leads to exclude the possibility of zipeprol treatment leading to addiction. The results of these studies allow zipeprol to be clearly distinguished from the opiate antitussives.

Animals↗
PubMedDate not supplied

[The investigation of the synchronization between rhythms in the human cardiovascular system from time series of R-R-intervals].

We demonstrated that, from the sequence of R-R intervals, it is possible to calculate the instantaneous phases and instantaneous frequencies of the main rhythmic processes governing the cardiovascular dynamics in humans, namely, the main heart rhythm, respiration, and the process of slow regulation of blood pressure with basic frequency close to 0.1 Hz. For the cases of spontaneous respiration and paced respiration with a fixed frequency, the synchronization between the rhythms of the cardiovascular system was investigated based on the analysis of only the time series of R-R intervals. It is shown that the main heart rhythm and the rhythm of low-frequency regulation of blood pressure can be synchronized with respiration.

Cardiovascular Physiological Phenomena↗
PubMed1990

The effects of calcium channel blockers on the cardiovascular system of rabbits in vivo.

The effects of i.v. administration of the calcium channel blockers--verapamil (0.045 and 0.45 mg.kg-1) and Mepamil (2-methylphenyl-derivative of verapamil; 0.0445 and 0.445 mg.kg-1) on the cardiovascular system of rabbits in vivo under the paced and non-paced heart conditions were investigated. Verapamil induced--in the dose-dependent manner--a decrease in blood pressure (max. 65.2%), a significant decrease in dP/dtmax. (max. 46.0%), a bradycardia (max. 79.4%), a decrease in minute blood flow (max. 63.9 %) and stroke blood flow (max. 71.5%). The administration of Mepamil did not induce important changes in heart rate; changes in other parameters were--again in the dose-dependent manner--of a similar qualitative character as after verapamil administration, but they were quantitatively less expressed (especially marked in the effect on dP/dtmax, where the maximum decrease was only to 71.5%). The results show a less pronounced cardiodepressive activity of Mepamil compared to verapamil in rabbits.

Animals↗