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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Bovine mesenteric lymphatics of 8 cm length were cannulated and arranged so that pressure changes produced by spontaneous contractions and accompanying flow could be measured. The mean frequency of spontaneous contractions, although constant for any one vessel, varied between vessels from 0.5 to 5.2 beats/min (mean 2.6, S.D. 1.6, n = 33). Noradrenaline (100 ng/ml.) invariably increased frequency of contractions but flow was increased only in those vessels which had a low resting frequency. In those vessels which had a higher resting frequency, flow was decreased despite the increase in frequency because stroke volume decreased. This may have been due to increased pace-maker activity causing desynchronization of the contractile activity in the vessel wall and thus decreased effectiveness of pumping. High doses (greater than 1 microgram/ml.) of noradrenaline invariably depressed flow. Isoprenaline slowed the frequency of spontaneous contractions and this either had little effect on flow (due to an increased filling time and thus stroke volume) or depressed it, finally abolishing it entirely at higher doses. It is concluded that in suitable dosage (which varies for different vessels) noradrenaline is capable of enhancing flow and this might, at least in part, explain the increase in lymph flow resulting from noradrenaline infusion in living animals.
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PMID:The effects of catecholamines on pumping activity in isolated bovine mesenteric lymphatics. 687 69

We investigated the influence of an intoxication with sparteine (10 mg/kg X min i.v.) on heart rate, arterial blood pressure, cardiac output, stroke volume and total peripheral resistance in anesthetized rats. The leading feature of the cardiovascular activity of sparteine in rats was a strong bradycardia whereas blood pressure, cardiac output and peripheral resistance only slightly decreased and stroke volume even increased. The death of the rats occurred with a sudden stop of the QRS complexes in the ECG and an abrupt fall of blood pressure. Isoprenaline, orciprenaline, dopamine and prenalterol were compared with respect to their efficacy in reversing sparteine-induced toxicity in rats. Prenalterol proved to be the best antidote on account of its specific action on adrenergic beta 1-receptors. This result was affirmed in two experiments in pigs. Isoprenaline may also be used as an antidote for sparteine but decreases the blood pressure. Vasoconstrictors like dopamine should only be used in sparteine intoxication when a severe fall of blood pressure occurs which can not be overcome by prenalterol or isoprenaline.
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PMID:[Experimental studies on therapeutic modification of sparteine poisoning]. 689 Dec 29

Cerebral ischemia was produced in the Mongolian gerbil by bilateral occlusion of the carotid arteries. Although the cerebral ischemia so produced was not total, a mortality rate of 100% was obtained if the occlusion was maintained for 60 min in gerbils weighing 45--55 gm. Few deaths were observed after 50 min of bilateral carotid arterial occlusion. Test drugs were administered, after the removal of the arterial clips, to groups of gerbils to determine the mortality rate associated with each drug. Isoproterenol 50 mg/kg, amphetamine 5.0 mg/kg, and methylprednisolone 35 mg/kg improved survival after cerebral ischemia. Atropine 1 mg/kg, thiosemicarbazide 4 mg/kg, aminooxyacetic acid 100 mg/kg, theophylline 100 mg/kg, and phenytoin 50 mg/kg were associated with a reduced survival after cerebral ischemia. The known tendency of the gerbil to exhibit spontaneous seizures and the frequency and severity of the observed post-ischemic seizures suggest that the lethality of prolonged cerebral ischemia may be, in part, related to seizures triggered by the cerebral ischemia.
Stroke
PMID:A gerbil model of cerebral ischemia suitable for drug evaluation. 698 34

Although isoproterenol is the sympathomimetic amine used most often to augment cardiovascular function in infants and children, little is known about the hemodynamic effects of this drug on the immature cardiovascular system. To compare the hemodynamic effect of isoproterenol in the young animal with that in the mature animal, we infused the drug into 11 puppies of 12-38 days of age, 12 puppies of 56-89 days of age and 10 adult beagle dogs. The animals were chronically instrumented and nonsedated during the study. Isoproterenol was infused in doses of 0.05, 0.125, 0.25 and 0.5 microgram/kg/min. Isoproterenol decreased systemic arterial mean blood pressure, increased heart rate and had no effect on renal blood flow in all three groups of animals. While cardiac output was increased and systemic vascular resistance decreased in the adult dogs, neither changed in puppies. Stroke volume increased slightly in adult dogs, but decreased in puppies. This refractoriness to change of cardiac output in immature dogs may be a function of elevated resting cardiac output, developmental changes of contractility or ventricular compliance or developmental changes of vascular smooth muscle responsiveness.
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PMID:The comparative hemodynamic effects of isoproterenol in chronically instrumented puppies and adult dogs. 747 10

To compare hemodynamic changes induced by isoproterenol and exercise stress tests in individuals with and without left ventricular volume load, we studied 10 lambs with an aortopulmonary shunt [58 +/- 4% (SE) of left ventricular output] 2 wk after the shunt was created. Two studies, isoproterenol infusion at 0.1 microgram.kg-1.min-1 and treadmill exercise at 76 +/- 4% of predetermined maximal O2 consumption (VO2) were performed in each lamb in random order on different days. Identical experiments were performed in nine lambs without shunts. Isoproterenol and exercise induced similar changes in heart rate (43 +/- 5%); systemic (72 +/- 7%), pulmonary (35 +/- 3%), and shunt blood flows (8 +/- 6%); and stroke volume (NS) in shunt lambs. Aortic systolic pressure increased less during isoproterenol infusion than during exercise (7 +/- 3 vs. 27 +/- 5%), and left atrial pressure decreased during isoproterenol infusion (-23 +/- 4%) but changed in an opposite direction during exercise (7 +/- 6%). These changes were accompanied by a smaller increase in myocardial VO2 during isoproterenol infusion than during exercise (5.0 +/- 0.7 to 5.3 +/- 0.6 and 5.3 +/- 0.8 to 7.3 +/- 0.9 mumol.beat-1 x 100 g-1, respectively). In control lambs, stroke volume decreased during isoproterenol infusion despite an equal decrease in left atrial pressure as in shunt lambs. In conclusion, isoproterenol better stimulates the blood flow changes during exercise in shunt than in control lambs probably because of their higher ventricular filling pressures. In interpreting isoproterenol stress tests it should, however, be kept in mind that these changes are realized at a lower work load for the heart.
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PMID:Effects of exercise and isoproterenol on hemodynamics and myocardial VO2 in lambs with aortopulmonary shunts. 804 29

Tremor has been rarely described as a manifestation of stroke. A 21-year-old left-handed man developed severe action tremor of his distal left upper extremity and hand following a right parieto-occipital intracerebral hemorrhage. Strength of the left upper extremity improved gradually during a 3-month period but a severe action tremor developed. The patient was treated with the cardioselective beta-blocking agent, metoprolol, initially for elevated blood pressure and tachycardia at 25 mg twice daily for approximately 2 months. Metoprolol was then increased at weekly intervals by 25mg twice daily to a total of 100mg twice daily. Tremor intensity decreased clinically and graphically as monitored by a trace test by having the patient attempt to trace a horizontal and vertical axis and scoring the errors. The scores declined weekly from the first week (4,347), second week (3,786), third week (1,088), to the fourth week (484). No adverse cognitive or cardiopulmonary effects were noted. Action tremor should be considered as one of the movement disorders caused by hemorrhagic cerebral infarction. This case responded well to treatment with metoprolol.
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PMID:Metoprolol for action tremor following intracerebral hemorrhage. 808 22

The purpose of the present study was to investigate the presence of putative cardiac beta 3-adrenoceptors mediating chronotropic and inotropic responses in normal subjects. Isoprenaline (a known beta 1, beta 2 and beta 3-agonist) was infused to stimulate cardiac beta-adrenoceptors in the presence of antagonists at beta 1 (atenolol 25 mg) and beta 1/beta 2 (nadolol 5 mg, 20 mg and 80 mg) adrenoceptor subtypes. Dose-ranging with nadolol was performed to evaluate the lowest dose required to produce significant beta 2-blockade, since the higher doses might conceivably cause beta 3-blockade. Doppler echocardiography was used to evaluate stroke distance and minute distance, which are the linear analogues of stroke volume and cardiac output respectively. Nadolol 5 mg produced almost complete blunting of finger tremor (beta 2-blockade) whilst atenolol 25 mg had no significant effect. Chronotropic and Doppler minute distance responses to isoprenaline were consistent with stimulation of both beta 1 and beta 2-adrenoceptors with no evidence of a beta 3-mediated effect. However, isoprenaline produced an increase in systolic blood pressure and left ventricular stroke distance that was not attenuated by a dose of nadolol (20 mg) which produced complete blunting of beta 1 and beta 2-mediated responses. This infers the possibility of functional inotropic or lusitropic beta 3-adrenoceptors in the human heart. This study also brings into question possible differences in the validity of using stroke distance and systolic blood pressure as measures of inotropic response to beta-adrenoceptor stimulation and advocates the use of Doppler echocardiography as an additional tool for this purpose.
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PMID:Investigation of putative cardiac beta 3-adrenoceptors in man. 839 10

Patients with diabetes mellitus that exhibit cardiac pump failure display compromised stroke volume, ejection fraction, and slower rates of rise and fall of left ventricular (LV) dP/dt in the absence of ischemic injury. We hypothesized that diabetic cardiomyopathy may involve decrements in adrenergic sensitivity, with specific molecular alterations in the beta-adrenergic receptor (beta AR)- G protein- adenylyl cyclase (AC) signal transduction system. We assessed the effects of 3 months of streptozotocin-induced diabetes (125 mg/kg i.v.; DIAB, n = 10) on myocardial signal transduction in mini-pigs. DIAB were hyperglycemic compared to controls (CON, n = 10; 20.92 +/- 2.64 v 5.24 +/- 0.35 mM glucose), and had lower fasting insulin levels (6.46 +/- 0.97 v 13.68 +/- 3.91 microU/ml). Transmural LV free wall homogenates from DIAB exhibited similar beta AR density as CON, but decreased cAMP production (pmol cAMP/mg prot.min) using these pharmacological stimulators: 10 microM Isoproterenol plus 100 microM GTP (74 +/- 5 v 97 +/- 11); 100 microM Gpp(NH)p (116 +/- 7 v 161 +/- 17); 10 mM fluoride ion (266 +/- 16 v 324 +/- 25). No differences between DIAB and CON were observed when stimulated by 100 microM forskolin (440 +/- 20 v 429 +/- 33), suggesting no alterations in the catalytic subunit of AC. In DIAB, quantitative immunoblotting indicated slightly depressed levels of Gs (552 +/- 44 v 630 +/- 59 pmol/g ww; NS), but a significant redistribution of alpha s from the sarcolemma to the cytosol (32.7 +/- 0.82% v 25.9 +/- 1.7%). Significantly elevated levels of cardiac Gi were seen in DIAB homogenates compared to CON ventricles (2326 +/- 145 v 1522 +/- 181 pmol/g ww), with no alpha i subunit redistribution. We conclude that despite maintained beta AR density, receptor-dependent and G protein-dependent stimulation of AC is depressed so that streptozotocin-induced diabetic LV is affected by increased cardiac Gi, redistribution of Gs alpha to the cytosol, and an increase in the Gi/Gs ratio. These results help explain depressed catecholamine responsiveness and cardiac performance exhibited by diabetic patients.
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PMID:Adrenergic desensitization in left ventricle from streptozotocin diabetic swine. 857 46

A 69-year-old woman was referred to our hospital with an aortic valve tumor. She had shown signs of chronic heart failure due to atrial fibrillation and hypertension for 4 years. There was no history of thromboembolism such as stroke and myocardial infarction, unaccountable fever, weight loss, and systemic symptoms. With two-dimensional echocardiography, a cardiac valve tumor was detected during a routine examination for heart failure. Echocardiographic findings showed a homogeneous mass with a diameter of approximately 1.5 cm, fixed directly to the noncoronary aortic valve cusp. During the operation, a papillary neoplasm, 1.5 by 1 cm, was observed at the midportion of the left ventricular side of noncoronary cusp without a peduncle. The tumor was excised together with all cusps. A 21-mm SJM aortic valve was implanted in position, and thereafter she remained free from symptoms. Histopathological examination of the tumor revealed benign papillary fibroelastoma. Two-dimensional echocardiography was utilized for a diagnosis of the aortic papillary fibroelastoma.
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PMID:[A case report of papillary fibroelastoma of the aortic valve]. 896 6

This study compared the effects of high-dose infusions of various adrenergic agonists on cardiovascular function in piglets. We hypothesized that agonists would have different effects on systolic, diastolic, and vascular functions. Nine anesthetized 3-week-old piglets underwent cardiac catheterization. Manometric and conductance catheters measured pressures and volumes. Data were acquired at rest and during infusions of epinephrine, norepinephrine, dopamine, dobutamine, isoproterenol, and phenylephrine. End-systolic elastance, preload-recruitable stroke work, cardiac output, the maximum and minimum derivatives of left ventricular pressure, the relaxation constant tau, peak filling rate, and end-diastolic stiffness were obtained. Contractile efficiency and the cardiac output/pressure-volume area ratio were calculated. Regression was used for analysis of variance; p < 0.05 was considered significant. All agonists increased indexes of contractility. beta-Adrenergic agonists enhanced relaxation. Isoproterenol and dopamine increased efficiency. No drug changed diastolic stiffness. Therefore both alpha-adrenergic and beta-adrenergic agonists have inotropic effects in the 3-week-old piglet. Some beneficial effects of beta-agonists on cardiac output may be due to enhancement of relaxation and to afterload reduction. Various agents exert different effects on the cardiovascular system, and these differences may be clinically important.
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PMID:Effects of commonly used adrenergic agonists on left ventricular function and systemic vascular resistance in young piglets. 902 63


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