PubMed Health⌕ Search

Biomedical subjects

J Bauersachs

Publications and source records attributed to J Bauersachs.

At least 19 recordsLinked to original sources
PubMed2006

Role of p38 mitogen-activated protein kinase in cardiac remodelling.

BACKGROUND AND PURPOSE: Mitogen-activated protein kinases (MAPK) are centrally involved in several mechanisms important for heart failure such as apoptosis, activation of inflammatory responses and cell proliferation. We therefore evaluated the effect of the selective p38 MAPK inhibitor SB 239063 on progression of left ventricular remodelling after myocardial infarction (MI) in rats. EXPERIMENTAL APPROACH: Rats were treated for 9 weeks with placebo or SB 239063 by gavage (15 mg kg(-1)) twice daily starting 7 days after ligation of the left anterior descending artery. Serial transthoracic echocardiography was performed at days 7, 36 and 70. KEY RESULTS: Over the 9 weeks, mortality was not different between the groups. On echocardiography, animals after myocardial infarction exhibited significant left ventricular dilatation as expected (week 10, end-systolic diameter, placebo sham 5.21+/- 0.34 vs. placebo MI 8.44+/- 0.57 mm). However, there was no difference between placebo and SB 239063-treated rats (week 10, end-systolic diameter, SB MI 7.76+/- 0.74 mm, not significantly different from placebo MI). Haemodynamics changed accordingly. Moreover, SB 239063 had no effect on left ventricular hypertrophy. Treatment with SB 239063 significantly reduced cytokine expression of tumour necrosis factor and interleukin-1beta after myocardial infarction. However, collagen content was not influenced by the treatment. CONCLUSION: Despite a reduction of inflammation, treatment with the p38 inhibitor SB 239063 does not affect cardiac remodelling and cardiac function when treatment is started 7 days after myocardial infarction.

Animals↗
PubMed2005

Cardiac regeneration by progenitor cells--bedside before bench?

Recent experimental and clinical trials give rise to the hope that progenitor cells could replace scar tissue after myocardial infarction with healthy functional myocardium. However, while a significant increase in left ventricular ejection fraction has been described after progenitor cell transplantation in several clinical trials, long-term results are lacking, and the mechanisms underlying the improvement of ejection fraction are unclear. Therefore, the efficacy of progenitor cell transplantation after myocardial infarction has not been established, and potential problems may have been underestimated. In-depth laboratory and animal studies are needed to determine the best cell type, optimal amount of cells, and time point for transplantation. Treatment of patients with progenitor cells outside well controlled prospective trials should be avoided.

Humans↗
PubMed2005

Endothelial progenitor cells as potential drug targets.

Endothelial progenitor cells (EPC) are bone marrow derived cells with the potential to differentiate into mature functional endothelial cells. First clinical trials have been performed investigating the effects of EPC transplantation into cardiac ischemic areas after myocardial infarction, in patients with peripheral atherovascular disease or on endothelialisation of artificial heart valves. Next to EPC transplantation, the pharmacological mobilisation and functional modification of EPC may also play a major role in future therapies. Studies have raised the concern that patients with coronary heart disease or severe heart failure may suffer from decreased amounts and impaired function of peripheral circulating EPC. Drug induced mobilization of EPC and normalization of EPC function may therefore improve prognosis of certain cardiovascular diseases. The underlying molecular events of a disturbed mobilisation, differentiation, homing and/or function of EPC are not well understood. In the present review we will highlight the current knowledge of the role of EPC dysfunction in various cardiovascular diseases and focus on potential causally related molecular mechanisms, which might be novel drug targets.

Animals↗
PubMed2004

Mineralocorticoid receptor antagonism and cardiac remodeling in ischemic heart failure.

Aldosterone production in the heart as well as aldosterone plasma levels are increased after myocardial infarction and in congestive heart failure, correlating with the severity of disease. Aldosterone promotes sodium and water retention, sympathoadrenergic activation, endothelial dysfunction, and cardiovascular fibrosis and hypertrophy. Even maximally recommended doses of ACE inhibitors do not completely prevent formation of aldosterone. The Randomized Aldactone Evaluation Study (RALES) and the Eplerenone Post acute myocardial infarction Heart failure Efficacy and SUrvival Study (EPHESUS) demonstrated that aldosterone receptor blockade markedly reduces mortality among patients with heart failure. This review summarizes recent clinical and experimental data on the effect of aldosterone antagonists on left ventricular remodeling and function in ischemic heart failure with special emphasis on potential underlying mechanisms. While reduction of excessive extracellular matrix turnover leading to decreased fibrosis appears to be the most important effect of mineralocorticoid receptor antagonism in heart failure, other mechanisms such as regression of hypertrophy, improvement of endothelial function, reduction of superoxide formation, and enhanced renal sodium excretion may contribute. Recent data showed that in rats with left ventricular dysfunction after extensive myocardial infarction, eplerenone on top of ACE inhibition more effectively improved cardiac remodeling and molecular alterations than ACE inhibition alone.

Aldosterone↗
PubMed2004

Heart failure, platelet activation and inhibition of the renin-angiotensin-aldosterone system.

Heart failure is a highly prevalent disease in aging western populations, associated with a substantially increased risk of thromboembolic events, not only in severe but even in mild to moderate stages. This can partly be attributed to concomitant atrial fibrillation, a well-known risk factor for stroke, as well as a "hypercoagulable state" including formation of intraventricular thrombi. Left ventricular dysfunction results in decreased cardiac output, pulmonary congestion and neurohumoral activation with marked stimulation of the renin-angiotensin-aldosterone system. Besides its contribution to progressive left ventricular remodelling, activation of the renin-angiotensin-aldosterone system is enhanced in the development of vascular endothelial dysfunction in heart failure, resulting in decreased nitric oxide bioavailability. Nitric oxide, however, controls vascular tone and inhibits platelet activation. Enhanced platelet activation has recently been described in patients with heart failure in sinus rhythm. This article summarises the potential contribution to platelet activation of vascular endothelial dysfunction and reduced formation of the platelet inhibitor nitric oxide, which increase further the risk for thromboembolic events in heart failure. Beneficial modulation of cardiac remodelling, left ventricular function, neurohumoral activation, endothelial dysfunction and platelet activation can be achieved by inhibition of the renin-angiotensin-aldosterone system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2003

Selective modulation of endogenous nitric oxide formation in ischemia/reperfusion injury in isolated rat hearts--effects on regional myocardial flow and enzyme release.

The role of nitric oxide (NO) in ischemia/reperfusion injury is controversial. We tested the role of inducible NOS (iNOS) in the ischemia/reperfusion injury in isolated rat hearts using the selective iNOS inhibitor S-methylisothiourea sulfate (SMT) and the non-selective NOS inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME). After 15 min of stabilization in Langendorff mode, hearts were perfused either with normal Krebs-Henseleit buffer, buffer containing 100 microM L-NAME, 0.5 microM SMT or 50 microM SMT for 5 min and were subjected to 25 min of ischemia followed by 30 min of reperfusion. Left ventricular developed pressure (LVDP) and total coronary flow (CF) were recorded continuously. After ischemia/reperfusion, a marked expression of iNOS protein was demonstrated by Western blotting, while virtually no iNOS protein was present in hearts without ischemia/reperfusion. Regional myocardial blood flow (RMBF) was measured with colored microspheres. Coronary vasoactive concentration of L-NAME and SMT depressed myocardial function as shown by decreased LVDP, dP/dt(max) and coronary.ow before ischemia. After ischemia the recovery of the total CF was impaired in L-NAME and 50 microM SMT pretreated hearts which was related to homogenous RMBF decrease in the right and left ventricle compared to that in control group. Low concentration SMT (0.5 microM) showed no coronary vasoactive effects before ischemia and attenuated ischemia/reperfusion injury indicated by lower ischemic contracture at 25 min of ischemia and reduced CK and LDH release during reperfusion. Thus, NOS inhibition did not affect blood flow distribution in rat hearts either in the pre-ischemic or reperfusion period. Selective iNOS inhibition reduced ischemic injury by reducing ischemic contracture and CK as well as LDH release during reperfusion.

Animals↗
PubMed2003

Acquired right coronary artery fistula draining to the right ventricle: angiographic documentation of first appearance following reperfusion after acute myocardial infarction, with subsequent spontaneous closure.

Most coronary artery fistulae are congenital in origin but have been reported to be acquired as complications of chest trauma, coronary angioplasty, or rupture of a coronary artery aneurysm. This is the first angiographic documentation of a coronary fistula acquired after myocardial infarction that subsequently closed spontaneously during follow up.

Chest Pain↗
PubMed2003

Aldosterone antagonism in addition to angiotensin-converting enzyme inhibitors in heart failure.

Although the role of the systemic renin-angiotensin-aldosterone system in the pathophysiology of heart failure is well-known for years, the impact of a local cardiac aldosterone system has been recognized recently. Aldosterone promotes cardiac hypertrophy and fibrosis in hypertension and heart failure and is involved in left ventricular remodeling after myocardial infarction. Plasma aldosterone levels in patients with heart failure are an indicator of a worse prognosis. Although ACE inhibitor therapy in these patients reduces plasma aldosterone levels, this effect is only transitory, a phenomenon referred to as "aldosterone escape". Even maximally recommended doses of ACE inhibitors do not completely prevent ACE-mediated formation of angiotensin II in chronic heart failure, and those patients with increased aldosterone levels during ACE inhibition have impaired exercise capacity. The RALES study has demonstrated convincingly that in patients with heart failure, addition of the mineralocorticoid receptor antagonist spironolactone (25 mg/d) to ACE inhibition markedly reduces mortality and prevents worsening heart failure. While reduction of excessive extracellular matrix turnover leading to decreased fibrosis appears to be the most important effect of spironolactone in heart failure, other mechanisms such as regression of hypertrophy, improvement of endothelial function, enhanced renal sodium excretion and antiarrhythmic actions may contribute. In RALES, low-dose spironolactone did not confer a substantial risk of hyperkalemia, however, with broader use of spironolactone in heart failure, cases of hyperkalemia associated with the use of this drug increase. Close control of serum potassium and creatinine and estimation of creatinine clearance are mandatory, especially in the presence of additional factors impairing renal function. The new and more selective aldosterone antagonist eplerenone which is devoid of some side effects of spironolactone, has been shown to be effective in hypertension and holds great promise as future therapeutic agent in patients with heart failure.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2002

Cytochrome P450 2C expression and EDHF-mediated relaxation in porcine coronary arteries is increased by cortisol.

OBJECTIVES/METHODS: In addition to nitric oxide (NO) and prostacyclin, endothelium-dependent dilation is mediated by the endothelium-derived hyperpolarizing factor (EDHF) which, in the coronary circulation, has been characterised as a metabolite of arachidonic acid synthesised by an cytochrome P450 (CYP) epoxygenase homologous to CYP 2C8/9. As the promotor regions of CYP 2C8 and 2C9 contain consensus sequences for glucocorticoid response elements, we determined the effect of cortisol on EDHF-mediated relaxations as well as on the expression of CYP 2C in isolated segments of porcine coronary artery. RESULTS: Bradykinin-induced NO-mediated relaxation of KCl-constricted arterial rings was slightly attenuated following exposure to cortisol. However, EDHF-mediated relaxations of U46619-constricted arterial rings assessed in the presence of the cyclo-oxygenase inhibitor diclofenac and the NO synthase inhibitor N(omega)nitro-L-arginine (0.3 mM), were significantly enhanced (maximum relaxation: 66+/-7%, P<0.05 vs. control rings: 36+/-8%). Cortisol treatment (0.1 microM, 24 h) did not affect the endothelium-independent relaxation elicited by sodium nitroprusside and acute incubation with cortisol (0.1 microM, 30 min) did not alter either NO- or EDHF-mediated responses. The expression of CYP 2C (quantified by RT-PCR, Western blot analysis and confocal microscopy) was enhanced in porcine coronary endothelial cells following incubation with cortisol for 18-24 h. CONCLUSIONS: These results demonstrate the concomitant upregulation of EDHF-mediated relaxations and CYP 2C expression by long-term treatment with cortisol. These observations support the concept that an epoxygenase homologous to CYP 2C8/9 plays a crucial role in the generation of EDHF-mediated responses in the coronary endothelium.

Animals↗
PubMed2002

High-altitude pulmonary edema: potential protection by red wine.

UNLABELLED: High-altitude pulmonary edema (HAPE) is the predominant cause of death due to high-altitude illness. At first sight, the observation that mountaineers regularly consume red wine in order to "feel better" seems to be paradoxical because, especially at higher altitudes, alcohol consumption could be detrimental. In this article, we review the potential mechanisms by which the components of red wine may beneficially affect the development of HAPE. DATA SYNTHESIS: The underlying cause of HAPE is the altitude-related reduction in barometric pressure, which leads to a decrease in partial pressure of oxygen in the alveolae and subsequently in the pulmonary capillaries and arterial system. Two cellular mechanisms have been described, both of which increase pulmonary vascular tone: enhanced endothelin 1 production and the increased generation of reactive oxygen species. Recent evidence has indicated that some of the compounds of red wine suppress endothelin 1 gene expression, and the anti-oxidative properties of red wine have been previously reported. CONCLUSION: This article briefly summarises the pathophysiological cellular events leading to HAPE and describes the potential mechanisms by which the ingredients of red wine may have a beneficial effect.

Altitude↗
PubMed2001

Improvement of left ventricular remodeling and function by hydroxymethylglutaryl coenzyme a reductase inhibition with cerivastatin in rats with heart failure after myocardial infarction.

BACKGROUND: Hydroxymethylglutaryl coenzyme A reductase inhibitors (statins) attenuate angiotensin II-induced cellular signaling. Because angiotensin II is involved in left ventricular (LV) remodeling after myocardial infarction (MI), we examined the effects of statin treatment in an experimental model of chronic heart failure after MI. METHODS AND RESULTS: Rats with extensive MI were treated with placebo or cerivastatin (0.3 mg/kg per day) as a dietary supplement or via gavage for 11 weeks starting on the 7th postoperative day. Infarct size and cholesterol levels were similar among all groups. LV cavity area, an index of LV dilatation, was reduced in MI rats on cerivastatin compared with placebo. LV end-diastolic pressure was increased in MI rats on placebo (24.1+/-4.1 mm Hg versus sham: 5.1+/-0.3 mm Hg; P<0.01), and it was significantly reduced by cerivastatin treatment (13.7+/-2.7 mm Hg; P<0.05 versus placebo). Cerivastatin partially normalized LV dP/dt(max) and dP/dt(min), indices of LV systolic and diastolic function, which were significantly reduced in MI rats on placebo. Improvement of LV function by cerivastatin was accompanied by a reduced expression of collagen type I and beta-myosin heavy chain. LV endothelial nitric oxide synthase was increased, whereas the nitrotyrosine protein level was decreased in MI rats by cerivastatin treatment. CONCLUSIONS: Cerivastatin improved LV remodeling and function in rats with heart failure. This effect was associated with an attenuated LV expression of fetal myosin heavy chain isoenzymes and collagen I. Statin treatment may retard the progression of chronic heart failure.

Animals↗
PubMed2001

Prevention of endothelial dysfunction in heart failure by vitamin E: attenuation of vascular superoxide anion formation and increase in soluble guanylyl cyclase expression.

OBJECTIVES: Enhanced vascular superoxide anion generation contributes to endothelial dysfunction in heart failure. However, the effect of long-term treatment with the antioxidant vitamin E is unknown. METHODS AND RESULTS: Relaxant responses were determined in aortic rings from Wistar rats with heart failure 12 weeks after myocardial infarction (MI) and compared with responses in tissues from sham-operated animals. From the seventh post-operative day, rats were given either a standard chow or a chow enriched in vitamin E (approximate intake 100 mg/day). In rings from rats with heart failure, acetylcholine-induced relaxation was attenuated (maximum relaxation, R(max) 54 +/- 3%) when compared with rings from sham-operated animals (79 +/- 3%, n=12, P < 0.01), while endothelium-independent relaxation elicited by sodium-nitroprusside was unchanged. Aortic superoxide generation was significantly enhanced in rats with heart failure. Vitamin E supplementation significantly improved acetylcholine-induced relaxation in rats with heart failure (R(max) 75 +/- 4%, P < 0.01) and led to a leftward shift in sodium-nitroprusside-induced relaxation curve. Aortic expression of the beta(1)-subunit of soluble guanylyl cyclase was significantly enhanced by vitamin E supplementation. In addition, the elevated vascular superoxide formation was normalised by vitamin E. CONCLUSIONS: These results demonstrate that dietary supplementation with the antioxidant vitamin E restores normal endothelial function, reduces vascular superoxide anion formation and increases the expression of the soluble guanylyl cyclase in rats with heart failure.

Acetylcholine↗
PubMed2001

Endogenous cannabinoids mediate hypotension after experimental myocardial infarction.

OBJECTIVES: We sought to determine whether endocannabinoids influence hemodynamic variables in experimental models of acute myocardial infarction (MI). BACKGROUND: Hypotension and cardiogenic shock are common complications in acute MI. Cannabinoids are strong vasodilators, and endocannabinoids are involved in hypotension in hemorrhagic and septic shock. METHODS: The early effect of left coronary artery ligation on hemodynamic variables was measured in rats pretreated with the selective cannabinoid(1) receptor (CB(1)) antagonist SR141716A (herein referred to as SR, 6.45 micromol/kg body weight intravenously) or vehicle. Endocannabinoids produced in monocytes and platelets were quantified by liquid chromatography/mass spectrometry (LC/MS), and their effects on blood pressure and vascular reactivity were determined. RESULTS: After MI, mean arterial pressure (MAP) dropped from 126 +/- 2 mm Hg to 76 +/- 3 mm Hg in control rats, whereas the decline in blood pressure was smaller (from 121 +/- 3 mm Hg to 108 +/- 7 mm Hg, p < 0.01) in rats pretreated with SR. SR increased the tachycardia that follows MI (change [Delta] in heart rate [HR] = 107 +/- 21 beats/min vs. 49 +/- 9 beats/min in control rats, p < 0.05). The MI sizes were the same in control rats and SR-treated rats. Circulating monocytes and platelets isolated 30 min after MI only decreased MAP when injected into untreated rats (DeltaMAP = -20 +/- 5 mm Hg), but not in SR-pretreated rats. The endocannabinoids anandamide and 2-arachidonyl glycerol were detected in monocytes and platelets isolated after MI, but not in cells from sham rats. Survival rates at 2 h after MI were 70% for control rats and 36% for SR-treated rats (p < 0.05). Endothelium-dependent arterial relaxation was attenuated in SR-treated rats (maximal relaxation: 44 +/- 3% [p < 0.01] vs. 70 +/- 3% in control rats) and further depressed by SR treatment (24 +/- 5%, p < 0.01 vs. MI placebo). CONCLUSIONS: Cannabinoids generated in monocytes and platelets contribute to hypotension in acute MI. Cannabinoid(1) receptor blockade restores MAP but increases 2-h mortality, possibly by impairing endothelial function.

Animals↗
PubMed2000

Striking increase of natriuresis by low-dose spironolactone in congestive heart failure only in combination with ACE inhibition: mechanistic evidence to support RALES.

BACKGROUND: A marked reduction of overall mortality in patients with severe congestive heart failure (CHF) has been demonstrated by addition of the mineralocorticoid receptor antagonist spironolactone to ACE inhibition. The aim of the present study was to examine a hypothesized interaction of spironolactone and ACE inhibitors in renal electrolyte and volume regulation. METHODS AND RESULTS: Wistar rats with extensive myocardial infarction or sham operation were treated with either placebo, the ACE inhibitor trandolapril, low-dose spironolactone, or a combination of the 2. Twelve weeks after infarction, rats were housed in metabolic cages. Urinary volume and sodium excretion were significantly increased in CHF rats on a combined treatment with spironolactone and trandolapril (21.2+/-2.6 mL/d, 2489+/-320 mmol/d, mean+/-SD; P<0.05 versus other experimental groups) versus placebo-treated rats (16.7+/-5.6 mL/d, 1431+/-458 mmol/d),whereas these parameters were not affected in rats on either spironolactone (16.1+/-6.6 mL/d, 1153+/-273 mmol/d) or trandolapril alone (15.9+/-4.2 mL/d, 1392+/-294 mmol/d). The effects on natriuresis coincided with a significant reduction of left ventricular end-diastolic pressure (LVEDP) in rats on trandolapril and spironolactone (10.8+/-8.2 mm Hg; P:<0.05 versus CHF placebo: 23.3+/-7.2 mm Hg; sham-operated rats: 5.1+/-0.9 mm Hg), whereas LVEDP remained elevated in rats treated with either compound alone. CONCLUSIONS: In the present study, we found an unexpected interaction of low-dose spironolactone and the ACE inhibitor trandolapril in experimental CHF leading to marked effects on renal electrolyte and volume regulation that were not apparent by treatment with either drug alone. These findings may explain the beneficial effects of spironolactone in CHF patients.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed2000

Endothelin-receptor blockade improves endothelial vasomotor dysfunction in heart failure.

OBJECTIVES: To elucidate the effect of selective endothelin ET(A)- and mixed ET(A/B)-receptor antagonists on endothelial vasomotor dysfunction in rats with heart failure after myocardial infarction (MI). METHODS: Vasoreactivity and superoxide anion formation were determined in aortic rings from Wistar rats 12 weeks after extensive MI (>46% of left ventricle) compared to sham-operated animals. Rats were either treated with the selective ET(A)-receptor antagonist LU 135252 (30 mg/kg/day), the mixed ET(A/B)-receptor antagonist Bosentan (100 mg/kg/day) or placebo. RESULTS: In MI rats, the concentration-response curve of the endothelium-dependent, nitric oxide-mediated relaxation induced by acetylcholine was significantly shifted to the right and the maximum relaxation was attenuated. Long-term treatment with both ET antagonists significantly improved acetylcholine-induced relaxation in MI rats. LU 135252 was more effective than Bosentan. Endothelium-independent relaxations induced by sodium nitroprusside as well as endothelin- and phenylephrine-induced contractions were similar in all groups of rats. Plasma renin activity and aortic superoxide formation, which were enhanced in rats with heart failure, were normalized by LU 135252, but not by Bosentan treatment. CONCLUSIONS: Long-term treatment with ET-receptor antagonists improves endothelial vasomotor dysfunction in rats with chronic MI. This mechanism may essentially contribute to the beneficial effects of ET receptor blockade in heart failure.

Acetylcholine↗
PubMed2000

Improvement of renal dysfunction in rats with chronic heart failure after myocardial infarction by treatment with the endothelin A receptor antagonist, LU 135252.

OBJECTIVE: To investigate the role of an activated endothelin system in the renal dysfunction observed in chronic heart failure after myocardial infarction. METHODS: In rats with heart failure after myocardial infarction and in sham-operated animals (Sham), we investigated the effect on renal function of long-term oral treatment with the selective endothelin A (ETA) receptor antagonist, LU 135252 (30 mg/kg per day; groups MI/LU and Sham/LU) or placebo (groups MI/P, Sham/P). Only animals with extensive myocardial infarction (at least 46% of the left ventricle) were included in the study. Infarct size was matched between groups MI/P and MI/LU. Endogenous creatinine clearance, fractional sodium excretion, and plasma and urinary concentrations of endothelin were determined 12 weeks after myocardial infarction. RESULTS: Endogenous creatinine clearance was significantly lower in group MI/P than in group Sham/P (MI/P: 0.64 +/- 0.05, Sham/P: 0.81 +/- 0.04 ml/min per 100 g body weight; P= 0.01 (means +/- SEM)). Treatment with LU 135252 completely prevented the decline in creatinine clearance in rats with chronic myocardial infarction (MI/LU: 0.98 +/- 0.21; Sham/LU: 0.83 +/- 0.10). Fractional sodium and protein excretion did not differ among the four groups. Group MI/P had a marked increase in plasma endothelin concentrations, which was not affected by treatment with LU 135252. Urinary endothelin excretion was significantly lower in group MI/P than in group Sham/P. In the treatment groups, no difference could be observed between animals that had suffered myocardial infarction and the sham-operated group, although LU 135252 markedly increased the urinary excretion of endothelin. CONCLUSION: Our data demonstrate a restoration of impaired renal function in chronic ischaemic heart failure by treatment with the selective ETA receptor antagonist, LU 135252. These results offer a promising therapeutic option for the treatment of renal insufficiency in patients with chronic heart failure.

Animals↗