Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Cardiovascular effects of centrally administered endothelin-1 (ET-1) were studied in control and propranolol-treated anesthetized rats using a radioactive microsphere technique. 2. In the control group, blood pressure, cardiac output, and stroke volume were decreased, and heart rate was not altered after the administration of ET-1.ET-1 produced a reduction in blood flow to the brain, heart, kidneys, gastrointestinal tract, portal system, musculoskeletal system, and skin. 3. Propranolol significantly attenuated the decrease in blood pressure, cardiac output and stroke volume induced by centrally administered ET-1. The reduction in blood flow to the brain, heart, kidneys, gastrointestinal tract, portal system, musculoskeletal system and skin induced by centrally administered ET-1 was blocked by propranolol. 4. It is concluded that centrally administered ET produces significant cardiovascular effects which are mediated through the sympathetic nervous system and could be antagonized by propranolol. These findings can also be helpful in explaining some of the beneficial effects of propranolol in various cardiovascular disorders involving central ET mechanisms.
 ...
PMID:Modification of systemic and regional circulatory effects of intracerebroventricular administration of endothelin-1 by propranolol in anesthetized rats. 890 86

1. When delayed neuronal death occurred in the hippocampus CA1 pyramidal cell layer of stroke-prone spontaneously hypertensive rats (SHRSP) at 4 and 7 days after a 10 min bilateral carotid occlusion and reperfusion, intense endothelin-1 (ET-1)- and ET-3-like immunoreactivities became evident in astrocytes in the damaged hippocampus CA1 subfields. 2. We also observed that microglia equipped with an ETB receptor aggregated within the CA1 pyramidal cell layer with neuronal death. 3. There was a dramatic increase in nitric oxide synthase (NOS) activity in astrocytes and microglia in the damaged hippocampus CA1 subfields. 4. Thus, the possibility that microglia with the ETB receptor are activated to produce NO, a neurotoxic factor, by astrocytic ET-1 and ET-3 produced in response to transient forebrain ischaemia would have to be considered.
 ...
PMID:Glial endothelin/nitric oxide system participates in hippocampus CA1 neuronal death of SHRSP following transient forebrain ischaemia. 907 89

In a porcine endotoxin shock model, the mixed nonpeptide endothelin receptor antagonist bosentan was administered 2 h after onset of endotoxemia (n = 8). Cardiopulmonary vascular changes, oxygen-related variables, and plasma levels of endothelin-1-like immunoreactivity were compared with a control group that received only endotoxin (n = 8). Bosentan abolished the progressive increase in mean pulmonary artery pressure and pulmonary vascular resistance seen in controls. Possible mechanisms include blockade of vasoconstrictive endothelin receptors, and a lesser degree of edema and inflammation indicated by less alveolar protein and a lower inflammatory cell count observed in bronchoalveolar lavage. Further, bosentan restored cardiac index to the pre-endotoxin level by an increase in stroke volume index, improved systemic oxygen delivery, and acid base balance. Because mean arterial blood pressure was unaffected, bosentan reduced systemic vascular resistance. Endotoxemia resulted in an increase in tumor necrosis factor-alpha and endothelin-1-like immunoreactivity plasma levels, the latter being further increased by bosentan. In conclusion, in porcine endotoxemia, treatment with the endothelin receptor antagonist bosentan, administered during fulminate shock, abolished pulmonary hypertension and restored cardiac index. These findings suggest that bosentan could be an effective treatment for reversing a deteriorated cardiopulmonary state during septic shock.
 ...
PMID:Cardiopulmonary dysfunction during porcine endotoxin shock is effectively counteracted by the endothelin receptor antagonist bosentan. 916 72

Endothelins are ubiquitously produced 21-amino-acid peptides that were discovered as an endothelial product and may play important roles in cardiovescular physiology and pathophysiology. The main endothelin produced by the endothelium is endothelin-1. The vasoconstrictor role of endothelins may participate in blood pressure elevation and vascular hypertrophy in salt-dependent models of hypertension (deoxycorticosterone acetate-salt hypertensive rats, spontaneously hypertensive rats treated with deoxycorticosterone, acetate and salt, and Dehl salt-sensitive rats), and in stroke-prone spontaneously hypertensive rats. In humans, endothelins may play important roles in moderate to severe essential hypertension, and in the hypertension of African-Americans. Endothelins may be involved in cardiac hypertrophy, and there is increasing evidence of their participation in heart failure, in which acute endothelin antagonism in humans exerts beneficial effects. Endothelin expression is enhanced in smooth muscle cells migrating into the intima of arteries in atherosclerosis, suggesting a role in atherogenesis. Endothelin may participate as a vasoconstrictor in coronary artery disease, and as a contributor to intimal proliferation in restenosis after coronary angioplasty. In patients with myocardial infarction, cardiac production of endothelin is increased, particularly in those with cardiogenic shock. There is a potential for participation of endothelins in vasospasm accompanying stroke or subarachnoid hemorrhage: in the latter, endothelin antagonism has shown beneficial effects in experimental models. In neonatal and in primary pulmonary hypertension, endothelin expression is enhanced, and in experimental models endothelin antagonism resulted in favorable responses. Systemic sclerosis is another, peripheral, form of vascular disease in which endothelin may play a role and in which endothelin antagonism may be an interesting therapeutic alternative. The pathophysiologic role of endothelins is becoming increasingly apparent in cardiovascular disease, generating interesting potential therapeutic targets for the use of endothelin antagonists or endothelin-converting enzyme inhibitors.
 ...
PMID:Clinical significance of endothelin in cardiovascular disease. 926 47

Centrally administered endothelin-1 (ET-1) produces a biphasic response, an initial increase followed by a decrease in blood pressure (BP). The pressor effect is due to stimulation of the sympathetic nervous system and/or release of vasopressin. The mechanism responsible for the depressor effect after central administration of ET-1 is still not known. Systemic and regional circulatory effects of intracerebroventricular (i.c.v.) administration of ET-1 (100 ng) were determined in anesthetized rats, using a radioactive microsphere technique. BP, cardiac output, and stroke volume were significantly decreased 30, 60, and 120 min after central administration of ET-1. Heart rate and total peripheral resistance were not altered. ET-1 produced a reduction in blood flow to the brain (83%), heart (62%), kidneys (53%), gastrointestinal tract (43%), portal system (46%), and musculoskeletal system (55%). To determine the role of the central nervous system in cardiovascular effects of centrally administered ET-1, experiments were performed in cervical-sectioned rats. The changes in systemic and regional blood circulation induced by centrally administered ET-1 in normal rats were not observed in cervical-sectioned rats. Pretreatment with a specific antagonist of ETA receptors, BQ-123 (10 micrograms i.c.v.), antagonized systemic and regional circulatory effects of ET-1. Centrally administered clonidine (1 microgram i.c.v.) produced hypotension and bradycardia, known to be mediated through the sympathetic nervous system. Pretreatment with an ETA receptor antagonist, BMS-182874 (50 micrograms/kg iv), blocked clonidine-induced hypotension and bradycardia. We conclude that centrally administered ET-1 stimulates ETA receptors to produce systemic and regional circulatory changes mediated by the sympathetic nervous system.
 ...
PMID:Role of sympathetic nervous system in cardiovascular effects of centrally administered endothelin-1 in rats. 932 4

Agonists acting on the vascular endothelium can modulate the release of a number of factors that interact with the surrounding smooth muscle cells and influence their tone. One such factor is the vasoconstricting agent endothelin-1 (ET-1), which has been implicated in several disease states, including stroke. However, very little is known about the physiological role of ET-1 in the cerebral circulation. We demonstrate that activation of alpha2-adrenoceptors in human pial artery endothelial cells reduces both constitutive and agonist-stimulated release of immunoreactive ET-1. That this has physiological relevance is supported by our demonstration that in segments of rabbit middle cerebral arteries, alpha2-adrenoceptor activation reduces the release of endothelium-derived ET-1 and causes an endothelium-dependent relaxation. The adrenoceptor-dependent relaxation was not blocked by combined addition of indomethacin and N omega-nitro-L-arginine in 25 mmol/L KCl-depolarizing physiological solution but was selectively antagonized by a subthreshold concentration of exogenous ET-1. Our data suggest that activation of endothelial alpha2-adrenoceptor would favor a decrease in ET-1 production and possibly promote vascular relaxation.
 ...
PMID:Reversal of endothelin-1 release by stimulation of endothelial alpha2-adrenoceptor contributes to cerebral vasorelaxation. 933 80

Brain swelling is a serious complication associated with focal ischemia in stroke and severe head injury. Experimentally, reperfusion following focal cerebral ischemia exacerbates the level of brain swelling. In this study, the permeability of the blood-brain barrier has been investigated as a possible cause of reperfusion-related acute brain swelling. Blood-brain barrier disruption was investigated using Evans Blue dye and [14C]aminoisobutyric acid autoradiography in a rodent model of reversible middle cerebral artery (MCA) occlusion. Acute brain swelling and cerebral blood flow (CBF) during ischemia and reperfusion were analyzed from double-label CBF autoradiograms after application of the potent vasoconstrictor peptide endothelin-1 to the MCA. Ischemia was apparent within ipsilateral MCA territory, 5 min after endothelin-1 application to the exposed artery. Reperfusion, examined at 30 min and 1, 2, and 4 h, was gradual but incomplete within this time frame in the core of middle cerebral artery territory and associated with significant brain swelling. Ipsilateral hemispheric swelling increased over time to a maximum (>5%) at 1-2 h after endothelin-1 but was not associated with a significant increase in the ipsilateral transfer constant for [14C]aminoisobutyric acid over this time frame. These results indicate that endothelin-1 induced focal cerebral ischemia is associated with an acute but reversible hemispheric swelling during the early phase of reperfusion which is not associated with a disruption of the blood-brain barrier.
 ...
PMID:Influence of ischemia and reperfusion on the course of brain tissue swelling and blood-brain barrier permeability in a rodent model of transient focal cerebral ischemia. 934 60

Several randomised studies have demonstrated that various nonsteroidal anti-inflammatory drugs (NSAIDs) elevate blood pressure in normotensive and hypertensive individuals; however, these data have been contradicted by numerous negative studies. Two meta-analyses have demonstrated that, after pooling data drawn from published reports of randomised trials of younger adults, NSAID use produces a clinically significant increment in mean blood pressure of 5 mm Hg, most marked in patients with controlled hypertension. Stratification by NSAID type revealed that piroxicam, naproxen and indomethacin had the greatest, and sulindac the smallest, pressor effect. These data were supported by 2 large community studies involving elderly patients. Recent NSAID users had a 1.7-fold higher risk of requiring the initiation of antihypertensive therapy compared with nonusers; NSAID users also had a 40% increased risk of receiving a diagnosis of hypertension compared with nonusers. It is vital to determine the nature of the association in the elderly, 12 to 15% of whom are concurrently receiving an NSAID and an antihypertensive agent. Importantly, a 5 to 6 mm Hg increase in diastolic blood pressure maintained over a few years may be associated with a 67% increase in total stroke risk and a 15% increase in coronary heart disease events. While the mechanism(s) remain speculative, salt and water retention through several factors operating in parallel, coupled with increased total peripheral vascular resistance, via increased renal endothelin-1 synthesis, are potentially important. Clinicians should strive to avoid excessive use of NSAID treatment and consider well-tolerated therapeutic alternatives, including simple analgesics and physical therapy. For patients who require concomitant NSAID and antihypertensive treatment, physicians should be aware that indomethacin, naproxen and piroxicam may be associated with a greater pressor effect than many other NSAIDs, and that antagonism of beta-blockers may be greater than that of vasodilators (including ACE inhibitors and calcium antagonists) and diuretics. Finally, the progress of each patient should be monitored by careful blood pressure measurement, particularly during the period of initiation of NSAID therapy.
 ...
PMID:NSAIDs and increased blood pressure. What is the clinical significance? 939 72

The use of nonsteroidal anti-inflammatory drugs (NSAIDs) and antihypertensive medication increases with age to 26% and > 50%, respectively, among the elderly. Overall, 12 to 15% of elderly individuals take at least 1 NSAID and an antihypertensive medication concurrently. A large case-control study of older individuals demonstrated that recent users of NSAIDs had a 1.7-fold increase in risk of initiating antihypertensive therapy compared with non-users. A community-based epidemiological study revealed that NSAID use significantly predicted the presence of hypertension (odds ratio 1.4, 95% confidence interval 1.1 to 1.7) in the elderly. Furthermore, among those taking antihypertensive agents in the 65+ Rural Health Study, in Iowa, US, individuals also taking NSAIDs had a mean systolic blood pressure (BP) 4.9 mm Hg higher than non-users of NSAIDs. The hypertensive effect of NSAIDs varies depending on the specific NSAID used and the type of antihypertensive agent, if they are taken concurrently. While the results of randomised, controlled trials in the elderly have been conflicting, 2 meta-analyses involving younger adults have revealed that NSAID use produces a clinically significant increment in mean BP of 5.0 mm Hg, which is most marked in patients with controlled hypertension. Stratification by NSAID type has revealed that piroxicam and indomethacin had the greatest, and sulindac the least, pressor effect. While the mechanisms) of the pressor effect remain speculative, salt and water retention, caused by several factors operating in parallel, coupled with an increased total peripheral vascular resistance via increased renal endothelin-1 synthesis, are potentially important. A 5 to 6 mm Hg increase in diastolic BP maintained over a few years may be associated with a 67% increase in total stroke occurrence and a 15% increase in events associated with coronary heart disease. Clinicians should strive to avoid excessive use of NSAID treatment and consider alternative, well-tolerated therapeutic options, including simple analgesics and physical therapy. For patients who require concomitant NSAID and antihypertensive treatment, clinicians should be aware of the greater hypertensive effect of indomethacin and piroxicam compared with alternative NSAIDs, and the potential for relatively greater antagonism by NSAIDs of the BP-lowering effect of beta-blockers compared with other antihypertensives. Finally, the progress of each patient should be monitored by careful BP measurement particularly during the initiation of NSAID therapy.
 ...
PMID:NSAIDs and blood pressure. Clinical importance for older patients. 946 84

The positive inotropy of endothelin-1 (ET-1) described by in vitro studies is not detectable in vivo because this effect is antagonized by cardiodepressive effects due to ET-induced vasoconstriction with subsequent myocardial ischemia. This vasoconstriction is mainly mediated by ETA receptors. In a previous in vivo study with a selective ETB receptor agonist, we showed that ETB receptors play an important role in the ET-induced positive inotropy. The present in vivo study examined whether selective ETA receptor blockade can unmask the ETB receptor-mediated positive inotropy of endogenous ET-1 by preventing its cardiodepressive effects via ETA receptors. In an open-chest rat model, we compared the acute hemodynamic and inotropic effects of the highly selective ETA receptor antagonist BQ-610 (100 micrograms/kg) with NaCl controls during and after a 7-min infusion. In addition to measurements in the intact circulation, the effects on myocardial contractility were studied by isovolumic registrations (peak LVSP, peak dP/dtmax), which are independent of peripheral vascular effects. Acute blockade of the ETA receptors by BQ-610 had no effect on blood pressure and heart rate. BQ-610 caused vasodilatation (total peripheral resistance -7.5% vs. control at the end of infusion; p < 0.01) with a consecutive increase in stroke volume (+15.3%; p < 0.01), cardiac output (+15.4%; p < 0.001), and ejection fraction (+10.4%; p < 0.01). The isovolumic measurements indicated a significant positive inotropic effect of BQ-610 (peak LVSP + 4.2%, p < 0.01; peak dP/dtmax + 5.5%, p < 0.01). Therefore, selective ETA receptor blockade by BQ-610 improves the hemodynamics in the intact circulation by causing a reduction in afterload and an increase in myocardial contractility. The positive inotropic effect of BQ-610 may be mediated by the positive inotropy of endogenous ET-1 via ETB receptors after selective ETA receptor blockade.
 ...
PMID:Hemodynamic and inotropic effects of the endothelin A antagonist BQ-610 in vivo. 959 54


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>