Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0018801 (heart failure)
 72,216 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The role of nitric oxide (NO) in congestive heart failure was investigated by studying the acute haemodynamic, hormonal and renal effects of N(G)-monomethyl-L-arginine (L-NMMA(, a nitric oxide inhibitor, given as incremental bolus doses in six sheep before (normal) and after induction of heart failure (HF) by rapid left ventricular pacing (LVoff+). 2. 6-NMMA caused significant initial dose-dependent rises in left ventricular systolic pressure, mean arterial pressure (MAP), peripheral resistance (PR) and left atrial pressure and declines in cardiac output in both normal and HF states (maximum response in 2-6 min). These responses were all but abolished when L-arginine was given concurrently with L-NMMA. The dose-response curve for the L-NMMA-induced rise in MAP was shifted to the right following LVP (P < 0.05), which is consistent with previous observations of blunted NO synthase activity in HF. A subsequent decline in MAP and PR to below prebolus levels was observed 30-60 min after L-NMMA administration in the paced state. No significant hormonal or renal effects were observed. 3. In conclusion, the present study confirms the important haemodynamic role played by endogenous NO in the normal state and demonstrates a blunted pressor response to NO inhibition in this model of heart failure.
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PMID:Nitric oxide inhibition in an ovine model of heart failure. 871 79

There is now considerable evidence that nitric oxide (NO) production and action are abnormal in patients with heart failure. Spontaneous NO release from the vascular endothelium is preserved or enhanced in patients with heart failure and this may help to maintain tissue perfusion by blunting the vasoconstriction induced by various neurohumoral factors. On the other hand, endothelial NO release in response to various stimuli including exercise appears to be diminished and this may contribute to the impaired exercise capacity of patients with heart failure. It is now apparent that NO produced within the heart plays an important role in the modulation of cardiac contractility under physiological conditions. In patients with heart failure, however, increased myocardial NO production in response to cytokines such as tumour necrosis factor-alpha may contribute to reduced contractility and myocyte injury. Our understanding of the role of NO in the control of vascular tone has provided an explanation for the efficacy of nitrovasodilators in heart failure and has stimulated novel approaches to augmenting endogenous vascular NO production. There is also evidence that ACE inhibitors act to restore normal endothelial function in patients with heart failure. Increased NO production within the heart, particularly that produced via the pro-inflammatory inducible NO synthase, may be detrimental. It remains to be determined whether selective inhibition of inducible NO synthase can favourably modify the course of this lethal condition.
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PMID:The role of nitric oxide in heart failure. Potential for pharmacological intervention. 873 29

We investigated the effects of inotropic agents with phosphodiesterase III inhibitory properties, amrinone, pimobendan and vesnarinone, and cell permeable cyclic nucleotide analogue, 8-bromo adenosine 3'5'-cyclic monophosphate (8 Br-cAMP) on the induction of nitric oxide synthase (NOS) by lipopolysaccharide in J774A.1 macrophages in vitro. Although all three inotropic agents inhibited nitrite accumulation, the degree of inhibition was different, with pimobendan being the most potent inhibitor and amrinone the least. Vesnarinone inhibited nitrite formation biphasically. 8 Br-cAMP increased nitrite production at high concentrations, suggesting that the inhibitory effects of inotropic agents could not be explained by an increase in cAMP. Although differential inhibition of inducible NOS by inotropic agents may explain the different effects of these drugs in patients with heart failure, further study is necessary to reach this conclusion.
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PMID:Inotropic agents differentially inhibit the induction of nitric oxide synthase by endotoxin in cultured macrophages. 876 21

Myocarditis is thought to be caused by various viruses, and accumulating evidence links viral myocarditis with the eventual development of dilated cardiomyopathy. Recently the importance of hepatitis C virus infection was noted in patients with dilated cardiomyopathy. Cytokines are increasingly recognized as an important factor in the pathogenesis and pathophysiology of myocarditis and cardiomyopathy. Elevated circulating cytokines have been reported in patients with heart failure, and various cytokines have been shown to depress myocardial contractility in vitro and in vivo. A number of recent studies showed that cytokines generated by activated immune cells cause an increase in NO (nitric oxide) via induction of NO synthase. Increased generation of NO may induce negative inotropism and myocardial damage. This review discusses the etiology and pathogenesis of myocarditis and cardiomyopathy from this point of view.
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PMID:Cytokines in myocarditis and cardiomyopathies. 883 73

Nitric oxide may act at autonomic sites in the brain to regulate sympathetic outflow. Our goal was to determine whether gene expression of the neuronal isoform of nitric oxide synthase (nNOS) is altered in discrete autonomic brain regions of rats in the chronic phase of heart failure compared to sham-operated control rats. Experiments were performed in rats 4 to 5 weeks after left coronary artery ligation. Histological data indicated that there was a 39% outer and a 45% inner infarct of the left ventricular myocardium in the heart failure group. The myocardium in sham-operated rats showed no observable damage. Total RNA was purified from microdissected brain tissue blocks containing hypothalamus, dorsal pons, dorsal medulla, rostral ventrolateral medulla, and caudal ventrolateral medulla. Changes in nNOS mRNA were semiquantified in each region using reverse transcription-polymerase chain reactions in which known concentrations of deletion mutant of the gene were coamplified as an internal standard. Compared with controls, significant decreases in nNOS mRNA levels were found in hypothalamus (19%), dorsal pons (43%) and dorsal medulla (34%) of rats with heart failure. There were no statistically significant differences in nNOS mRNA levels in rostral or caudal ventrolateral medulla between the control and heart failure groups. Concomitant with the changes nNOS gene expression in central sites, the plasma concentration of norepinephrine was significantly elevated in rats with heart failure compared to sham-operated control rats. Our results show that heart failure is associated with decreases in nNOS gene expression in at least three regions of the brain and with increased sympathetic outflow to the periphery. The decreased NO production that is likely associated with the decreases in nNOS gene expression may lead to the increased sympathetic drive seen in chronic heart failure.
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PMID:Decreased gene expression of neuronal nitric oxide synthase in hypothalamus and brainstem of rats in heart failure. 889 16

Nitric oxide (NO), the free radical that accounts for the biological activity of endothelium-derived relaxing factor, is synthesized from L-arginine by NO synthase (NOS). There is evidence that NO availability is reduced in the peripheral vasculature of patients with congestive heart failure (CHF). The aim of this study was to investigate the expression of NOS in the descending aorta and in the skeletal muscles of rats subjected to heart failure. The alkaloid, monocrotaline, was used to induce pulmonary hypertension and cardiac failure in rats. The expression of both the constitutive (ecNOS) and the inducible (iNOS) isoforms of the enzyme was assessed by Western blot analysis. In CHF animals, the ecNOS location in the aorta is altered: the endothelial protein expression is substantially reduced (from 0.083 +/- 0.012 to 0.003 +/- 0.004 OD/microgram total proteins, P < 0.001) whereas the expression of ecNOS in the smooth muscle is increased (from 0.024 +/- 0.004 to 0.059 +/- 0.009 OD/ microgram total proteins, P < 0.01). The total aortic ecNOS is diminished in CHF respect to control animals (0.062 +/- 0.009 v 0.107 +/- 0.013 OD/microgram total proteins, P < 0.01). On the contrary, no difference in ecNOS protein expression was observed in the extensor digitorum longus and soleus muscles. Furthermore, iNOS was not detected in any of the tissues considered. In conclusion, experimental CHF causes a re-setting of the ecNOS protein expression in the descending aorta but not in skeletal muscles. The reduced abundance of ecNOS in the aortic endothelium is consistent with the impairment of the vasodilating function reported in patients with CHF.
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PMID:Aorta and skeletal muscle NO synthase expression in experimental heart failure. 893 77

To characterize vasodilator capacity of small coronary arteries (200-350 microm diameter) in the setting of congestive heart failure, we examined relaxation responses to acetylcholine (10(-9)-10(-4) M) and nitroglycerin (10(-9)-10(-4) M), in the absence and presence of the nitric oxide precursor, L-arginine (10(-4) M). Congestive heart failure was reliably induced in dogs by rapid ventricular pacing (250 beats.min(-1) for 4 weeks). Maximum relaxations (means +/- S.E.) to each vasodilator are expressed as a percentage of the relaxation response to papaverine (10(-4) M). Relaxation responses to the endothelium-dependent relaxing agent, acetylcholine, were not altered at heart failure, or in the presence of L-arginine. Contrary to acetylcholine, relaxations to nitroglycerin were significantly enhanced in heart failure compared to control (83 +/- 25% vs. 25 +/- 6%, respectively, P < 0.05). Although L-arginine, alone, did not cause any vasodilator response in coronary microvessels, it was able to potentiate nitroglycerin relaxations at control (no L-arginine: 25 +/- 6% vs. L-arginine: 135 +/- 66%). In contrast, at heart failure, L-arginine diminished nitroglycerin relaxations (no L-arginine: 83 +/- 25%, vs. L-arginine: 48 +/- 15%). These data indicate a unique vasodilator profile in small coronary arteries at heart failure: endothelium-dependent relaxations are unaltered, whereas responses to nitroglycerin are augmented. Addition of the nitric oxide precursor, L-arginine, did not affect acetylcholine relaxation, yet surprisingly had a differential effect in response to nitroglycerin. Moreover, inhibition of nitric oxide synthase with N(omega)-nitro-L-arginine elicited concentration-dependent constriction in heart failure but not control coronary microvessels. In summary, our study suggests an important role for nitric oxide in vasodilator control of coronary microvessels, which may modify nitrovasodilator therapy in congestive heart failure.
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PMID:Altered vasodilator response of coronary microvasculature in pacing-induced congestive heart failure. 901 29

We have previously proposed that pro-inflammatory cytokines and nitric oxide (NO) contributed to reversible myocardial depression in patients with sepsis and congestive heart failure. Sepsis and heart failure are also associated with refractoriness to beta-adrenoceptor agonists. Therefore, the chronotropic effects of cytokines and the NO synthase inhibitor, NG-methyl-L-arginine (NMA), on beta-adrenoceptor stimulation of neonatal cardiac myocytes were studied. Tumor necrosis factor alpha, interleukin-1 beta and interleukin-6 but not interleukin-4 or interleukin-5 significantly enhanced spontaneous beating rates compared to untreated myocytes in serum-free media for 48 h (P < 0.01; n = 12 for each). NMA also significantly enhanced spontaneous beating rates (P < 0.01; n = 12 for each). Only interleukin-1 beta treatment resulted in significant nitrite production, immunohistochemical staining for inducible nitric oxide synthase and detection of inducible NO synthase messenger RNA by reverse transcriptase-polymerase chain reaction (RT-PCR). However, tumor necrosis factor alpha, interleukin-1 beta, interleukin-6, and NMA each completely blocked the positive chronotropic effects of the beta-adrenoceptor agonist, isoproterenol (P < 0.01; n = 12 for each). These findings are most consistent with an inducible NO synthase-independent effect of cytokines and NMA on the chronotropic responses of neonatal cardiac myocytes to beta-adrenoceptor stimulation. This effect of cytokines and NMA on adrenergic signaling may involve a myocardial constitutive NO synthase or an NO-independent mechanism.
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PMID:Cytokines and nitric oxide synthase inhibitor as mediators of adrenergic refractoriness in cardiac myocytes. 905 50

Norepinephrine and epinephrine stimulate alpha- and beta-adrenergic receptors which, in turn, modulate force of contraction in heart muscle cells. However, chronic stimulation may be associated with growth-promoting effects and modulation of the cardiac phenotype. Sympathetic tone is chronically enhanced in chronic heart failure and results in a selective down regulation of beta 1 adrenergic receptors, most likely due to local mechanisms. Beyond reduced beta 1 receptor density and increased levels of inhibitory Gi proteins, there is now evidence that NO can modulate the beta-adrenergic stimulation in the human myocardium. Increased NO activity generated by an inducible NO synthase is associated with a reduced positive inotropic response to beta-agonists, a mechanism which may play an important role in inflammatory states such as myocarditis or sepsis. Experimental data suggests that stimulation of alpha-adrenergic receptors of cardiomyocytes results in cardiac growth and changes in phenotype which, in turn, may affect the functional properties of the myocardium. For example, phenylephrine can upregulate the expression of the sodium/calcium exchanger, while the expression SR Ca2+ ATPase may be reduced. The latter is also affected by angiotensin II. Similar changes in the expression of these crucial proteins for the cardiac calcium homeostasis have been reported in the failing human heart, raising the possibility that the increased sympathetic tone and the activated renin-angiotensin system may be involved in these changes.
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PMID:[Sympathetic nervous system in heart failure: effect of catecholamines and nitric oxide]. 906 72

Recent evidence suggests that newer vasoselective dihydropyridine calcium antagonists are not cardiodepressant and may be useful in the treatment of heart failure. No data are available on the efficacy of clentiazem, a vasoselective benzothiazepine-like calcium antagonist, in this pathological condition. Therefore, our objective was to assess coronary and cardiac sensitivity to clentiazem in an experimental model of chronic heart failure (cardiomyopathic hamster, UM-X7.1, > 200 day old). Left ventricular developed pressure (LVP) and coronary flow changes were assessed in isolated, perfused failing hearts and in normal Syrian hamster hearts. Clentiazem dose-response curves for both coronary dilation and negative inotropic effects were determined under control conditions and in the presence of the nitric oxide (NO) synthase inhibitor, NG-nitro-L-arginine (L-NAME, 30 microM), and the cyclooxygenase inhibitor, indomethacin (10 microM). Baseline hemodynamics indicate a significant reduction in both LVP and coronary perfusion in failing hearts. Cardiac sensitivity to the negative inotropic effects of clentiazem were similar in normal and failing hearts (IC50 = 677 nM and 734 nM, respectively). However, the clentiazem-induced increase in coronary flow was significantly attenuated in failing hearts (EC50 = 56 +/- 9 nM vs. 15 +/- 3 nM in normal hearts, p < 0.01). To better characterize the reduced coronary sensitivity to clentiazem in the presence of heart failure, the contributions of the NO synthase and the cyclooxygenase pathways were evaluated. Although coronary sensitivity to clentiazem was significantly reduced in the presence of L-NAME, this attenuation was of the same magnitude in normal and failing hearts, suggesting that coronary "desensitization" to clentiazem in failing hearts does not involve the NO synthase pathway. Experiments carried in the presence of indomethacin indicate that the reduced coronary sensitivity to clentiazem observed in failing hearts does not involve the cyclooxygenase pathway. In conclusion, reduced coronary sensitivity to the vasoselective calcium antagonist clentiazem was observed in the failing hamster heart, while no exacerbation of clentiazem's cardiodepressant actions was present. Although the mechanisms involved in the vascular desensitization to clentiazem are still unknown, our findings may provide an additional explanation for the variable efficacy of calcium antagonists in the treatment of heart failure.
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PMID:Coronary and cardiac sensitivity to the vasoselective benzothiazepine-like calcium antagonist, clentiazem, in experimental heart failure. 914 Jun 81


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