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)

In patients with congestive heart failure (CHF), the distribution of the cardiac output is altered. Cardiopulmonary and arterial baroreceptors normally can regulate regional blood flow, but their contribution in heart failure is not known. To examine the role of baroreceptors in the regulation of regional blood flow in CHF, the effect of lower body negative pressure (LBNP) on forearm, renal, and splanchnic blood flow was evaluated in 12 patients with heart failure. Incremental LBNP at -10 and -40 mmHg decreased central venous pressure but had not effect on systolic blood pressure or pulse pressure. Renal blood flow decreased from 505 +/- 63 to 468 +/- 66 ml/min during LBNP -10 mmHg (P less than 0.05) and to 376 +/- 74 ml/min during LBNP -40 mmHg (P less than 0.01). Splanchnic blood flow decreased from 564 +/- 76 to 480 +/- 62 ml/min during LBNP -10 mmHg (P less than 0.01) and to 303 +/- 45 ml/min during LBNP -40 mmHg (P less than 0.01). Forearm blood flow did not decrease during LBNP -10 mmHg or -40 mmHg. To determine whether the absence of limb vasoconstriction during LBNP was confined to abnormalities in the baroreflex arc or was secondary to impaired end-organ responsiveness, six patients with heart failure and six normal subjects received an intrabrachial artery infusion of phenylephrine. Phenylephrine increased forearm vascular resistance comparably in each group. These data demonstrate that baroreceptors can regulate splanchnic and renal but not limb vascular resistance in patients with congestive heart failure and may contribute to the redistribution of blood flow that occurs in this disorder.
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PMID:Baroreflex regulation of regional blood flow in congestive heart failure. 233 75

In clinical and experimental heart failure, the inotropic response to beta-adrenergic receptor stimulation is depressed. Therefore, non-beta-adrenergic mechanisms may assume increasing importance for summoning inotropic reserve in the failing heart. To test the integrity of the inotropic pathway mediated by alpha 1-adrenergic receptor stimulation in a model of chronic ischemic heart failure, we administered phenylephrine to noninfarcted left ventricular papillary muscles isolated from sham-operated rats (n = 10) and rats with large (> 40% left ventricular circumference) anterior myocardial infarctions (n = 9). Isometric force was monitored, and intracellular Ca2+ (Cai2+) transients were recorded with the bioluminescent protein aequorin. Compared with muscles from sham-operated rats, contractility of muscles from rats with postinfarction heart failure was depressed at extracellular Ca2+ concentrations between 0.5 and 3.0 mM. Phenylephrine produced comparable dose-dependent increases in developed tension (126 +/- 4 vs. 125 +/- 7% of baseline) and peak rate of tension rise (125 +/- 4 vs. 140 +/- 9% of baseline) in muscles from sham and infarcted rats, respectively. There was no significant change in the time course of the isometric twitch or in the time course or amplitude of the Cai2+ transient after phenylephrine administration in muscles from either group. No evidence of Cai2+ overload, as defined by spontaneous Ca2+ release, was observed during phenylephrine administration in muscles from normal or failing hearts. The density of alpha 1-adrenoceptors measured with [3H]prazosin binding in crude membranes isolated from noninfarcted left ventricular tissue was not different in control and infarcted hearts (48 +/- 5 vs. 53 +/- 4 fmol/mg protein). These data indicate that the positive inotropic effect of alpha-agonists may be preserved in chronic ischemic heart failure. In both normal and failing myocardium, the inotropic effects of alpha 1-adrenergic stimulation occurred with little or no increase in Cai2+ availability and no apparent adverse effects on myocardial relaxation. Therefore, agents that act by similar mechanisms may have certain therapeutic advantages over traditional inotropic agents in patients with heart failure.
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PMID:Inotropic effects of alpha 1-adrenergic agonists in myocardium from rats with postinfarction heart failure. 750 48

The objective of this study was to evaluate the tension-frequency relationship in normal and cardiomyopathic myocardium from one species with a negative or biphasic relationship, the hamster, and one with a positive relationship, the dog. Left ventricular papillary muscles from 100-day-old normal Syrian and cardiomyopathic (CHF-147) hamsters and right ventricular papillary muscles or trabeculae from normal mongrel dogs and dog with pacing-induced heart failure were used for the study. Stimulation frequency was varied from 1 to 90/min and isometric contractions recorded at each frequency prior to and after the addition of phenylephrine 10 microM. A tension-frequency relationship at varying extracellular calcium concentrations (1.25, 2.5 and 5.0 mM) was also constructed in normal hamster myocardium. Ryanodine 1.2 microM was added to a bath with normal hamster muscles and a force-frequency relationship constructed prior to and after adding phenylephrine 10 microM. A calcium dose-response curve in normal and cardiomyopathic dog myocardium was also constructed. Normal and cardiomyopathic hamster myocardium had a biphasic tension-frequency relationship with the increase in tension during the second phase being greater in normal v cardiomyopathic hamster myocardium (0.66 +/- 0.19 v 0.12 +/- 0.03 g/mm2, P < 0.05). The initial decrease in tension in response to increasing stimulation frequency was markedly attenuated in normal hamster myocardium by increasing extracellular calcium concentration. Developed tension was eliminated at lower stimulation rates by ryanodine such that when developed tension did occur, it increased with increasing stimulation rates. The addition of phenylephrine to hamster myocardium modified the tension-frequency relationship of both normal and cardiomyopathic dog myocardium and their response to phenylephrine were similar. In each case, tension increased progressively with increasing stimulation rate. Although the absolute increase in tension caused by increasing extracellular calcium was less in cardiomyopathic dog myocardium, the percent increase in tension and shortening was greater. We conclude that the tension-frequency relationship of normal and cardiomyopathic hamster myocardium are biphasic, with the initial negative phase being the result of limitations of sarcoplasmic reticulum calcium handling. Phenylephrine modifies this relationship to a uniphasic positive one, likely by its effects on both the sarcolemma and the sarcoplasmic reticulum. Also, the tension-frequency relationship of normal and cardiomyopathic dog myocardium are similar and unmodified by phenylephrine.
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PMID:Tension-frequency relationships in normal and cardiomyopathic dog and hamster myocardium. 853 Dec 7

The mechanisms by which sympathetic function is augmented in chronic heart failure (CHF) are not well understood. A previous study from this laboratory (Circ Res. 1998;82:496-502) indicated that blockade of nitric oxide (NO) synthesis resulted in only an increase in renal sympathetic nerve activity (RSNA) when plasma angiotensin II (Ang II) levels were elevated. The present study was undertaken to determine if NO reduces RSNA in rabbits with CHF when Ang II receptors are blocked. Twenty-four New Zealand White rabbits were instrumented with cardiac dimension crystals, a left ventricular pacing lead, and a pacemaker. After pacing at 360 to 380 bpm for approximately 3 weeks, a renal sympathetic nerve electrode and arterial and venous catheters were implanted. Studies were carried out in the conscious state 3 to 7 days after electrode implantation. The effects of a 1-hour infusion of sodium nitroprusside (SNP; 3 microgram . kg-1. min-1) on RSNA and mean arterial pressure (MAP) were determined before and after Ang II blockade with losartan (5 mg/kg) in normal and CHF rabbits. Changes in MAP were readjusted to normal with phenylephrine. Before losartan, SNP evoked a decrease in MAP and an increase in RSNA in both groups that was baroreflex-mediated, because both MAP and RSNA returned to control when phenylephrine was administered. In the normal group, losartan plus SNP caused a reduction in MAP and an increase in RSNA that was 152.6+/-9.8% of control. Phenylephrine returned both MAP and RSNA back to the control levels. However, in the CHF group, losartan plus SNP evoked a smaller change in RSNA for equivalent changes in MAP (117.1+/-4.1% of control). On returning MAP to the control level with phenylephrine, RSNA was reduced to 65.2+/-2.9% of control (P<0. 0001). These data suggest that endogenous Ang II contributes to the sympathoexcitation in the CHF state and that blockade of Ang II receptors plus providing an exogenous source of NO reduces RSNA below the elevated baseline levels. We conclude that both a loss of NO and an increase in Ang II are necessary for sustained increases in sympathetic nerve activity in the CHF state.
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PMID:Regulation of sympathetic nerve activity in heart failure: a role for nitric oxide and angiotensin II. 1006 76

Alpha1-adrenergic stimulation, coupled to Gq, has been shown to promote heart failure. However, the role of alpha1-adrenergic signaling in the regulation of myocardial contractility in failing myocardium is still poorly understood. To investigate this, we observed 1) the effect of phenylephrine on myofibrillar Ca2+ sensitivity in alpha-toxin-skinned cardiomyocytes, and 2) protein expression of Gq, RhoA, and myosin light chain phosphorylation using tachypacing-induced canine failing hearts. Phenylephrine significantly increased myofibrillar Ca2+ sensitivity in failing but not in normal cardiomyocytes. Whereas Y-27632 (Rho kinase inhibitor) blocked the phenylephrine-induced Ca2+ sensitization in the failing myocytes, calphostin C (protein kinase C inhibitor) had no effect on Ca2+ sensitization. The protein expression of Galpha(q) and RhoA and the phosphorylation level of regulatory myosin light chain significantly increased in the failing myocardium. Our results suggest that alpha1-adrenoceptor-Gq signaling is upregulated in the failing myocardium to increase the myofibrillar Ca2+ sensitivity mainly through the RhoA-Rho kinase pathway rather than through the protein kinase C pathway.
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PMID:Alpha1-adrenoceptor-Gq-RhoA signaling is upregulated to increase myofibrillar Ca2+ sensitivity in failing hearts. 1145 67

Plasma adenosine levels are elevated in cardiovascular disease including hypertension and heart failure, and the nucleoside has been proposed to serve as an endogenous antimyocardial remodeling factor. We studied the modulation of phenylephrine-induced hypertrophy by adenosine receptor activation in isolated neonatal cultured ventricular myocytes. Phenylephrine (10 muM) increased cell size by 35% and significantly increased expression of atrial natriuretic peptide. These effects were reduced by the stable adenosine analog 2-chloroadenosine and were completely blocked by the adenosine A(1) receptor agonist N(6)-cyclopentyladenosine (1 microM), the A(2A) receptor agonist 2-p-(2-carboxyethyl)-phenethylamino-5'-N-ethylcarboxamidoadenosine (100 nM), and the A(3) receptor agonist N(6)-(3-iodobenzyl)adenosine-5'-methyluronamide (100 nM). The antihypertrophic effects of all three agonists were completely reversed by their respective antagonists. Phenylephrine significantly up-regulated expression of the immediate early gene c-fos especially within the first 30 min of phenylephrine treatment. These effects were almost completely inhibited by all adenosine receptor agonists. Although phenylephrine also induced early stimulation of both p38 mitogen-activated protein kinase and extracellular signal-regulated kinase, these responses were unaffected by adenosine agonists. The expression of the G-protein regulatory factors RGS2 and RGS4 were increased by nearly 3-fold by phenylephrine treatment although this was completely prevented by adenosine receptor agonists. These agents also blocked the ability of phenylephrine to up-regulate Na/H exchange isoform 1 (NHE1) expression in hypertrophied myocytes. Thus, our results demonstrate an antihypertrophic effect of adenosine acting via multiple receptor subtypes through a mechanism involving down-regulation of NHE1 expression. The ability to prevent regulators of G-protein signaling (RGS) up-regulation further suggests that adenosine receptor activation minimizes signaling which leads to hypertrophic responses.
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PMID:Inhibition of phenylephrine-induced cardiomyocyte hypertrophy by activation of multiple adenosine receptor subtypes. 1545 91

Cardiac hypertrophy and heart failure occur in association to alterations in glucose uptake and metabolism. Phenylephrine, among other hypertrophic agonists, has been reported to increase expression of GLUT1 in neonatal rat cardiac myocytes by activating transcription. However, the specific cis- or trans-acting factors in the GLUT1 gene that are targeted by this agonist remain elusive. Here we describe that the activity of the -99/+134 basal promoter of rat GLUT1 is increased by phenylephrine. Nevertheless, this is not mediated by previously described binding sites (GC-box, MG1E) in the promoter. Rather, the TATA box is required by the agonist to activate transcription from the promoter. Interestingly, The Ras-ERK mitogen-activated protein (MAP) kinase pathway is involved in the actions of phenylephrine on GLUT1 transcription, and the effects of Ras on the activity of the promoter depend on the integrity of the TATA box. Our data indicate that phenylephrine induces the expression of the TBP-associated factor TAF(II)250 mRNA, which increases in parallel to the expression of GLUT1, suggesting that altering the expression of basal transcription factors could be one mechanism by which phenylephrine may regulate the activity of the GLUT1 promoter.
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PMID:Phenylephrine requires the TATA box to activate transcription of GLUT1 in neonatal rat cardiac myocytes. 1580 44

1. Alterations in a(1)-adrenoceptor signalling that result in enhanced contraction in resistance arteries in heart failure are not well characterized. To clarify whether this enhanced constriction is due to Ca(2+)-dependent or -independent effects, we measured the phenylephrine-induced changes in [Ca(2+)](i) in the presence of a Rho kinase inhibitor or an inositol 1,4,5-trisphosphate (IP(3)) receptor inhibitor. 2. Heart failure was induced in rats by ligation of the left coronary artery. Changes in the internal diameter of pressurized small femoral arteries were examined using videomicroscopy. Phenylephrine concentration-response curves, constructed in the presence of the Rho kinase inhibitor Y27632 (0.3 micromol/L) or the IP(3) receptor inhibitor xestospongin C (0.3 micromol/L), were compared in heart failure rats and sham-operated (control) rats; fura-2 Ca(2+) signals were measured in the arteries of both groups. 3. The heart : bodyweight ratio, lung : bodyweight ratio, left ventricular end-diastolic pressure and plasma B-type natriuretic peptide were significantly higher in heart failure rats compared with control rats. Phenylephrine-induced contractile responses and increases in [Ca(2+)](i) were significantly greater in arteries from heart failure rats compared with arteries from control rats. At 0.3 micromol/L, Y27632 selectively inhibited phenylephrine-induced constrictions of heart failure arteries, but had no effect on the increase in [Ca(2+)](i). 4. Immunohistochemical staining for Rho kinase was greater in heart failure rats compared with control rats. 5. The degree of inhibition of both the phenylephrine-induced constriction and the increase in [Ca(2+)](i) by xestospongin C (0.3 micromol/L) was greater in arteries from heart failure rats than in those from control rats. 6. The increased contractile response to phenylephrine in arteries of heart failure rats results from IP(3)-dependent increases in [Ca(2+)](i) and from an enhanced Ca(2+) sensitivity via a Rho kinase-dependent mechanism.
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PMID:Mechanism of increased alpha-adrenoceptor-mediated contraction in small resistance arteries of rats with heart failure. 1644 98

This study assessed the effects of short-term adrenoceptor blockade on plasma matrix metalloproteinase (MMP) activity in patients with heart failure, and the ability of adrenoceptor stimulation to modulate matrix metalloproteinase-9 (MMP-9) promoter activity in vitro. Patients with heart failure received standard therapy or standard therapy plus carvedilol. Plasma MMP activity was determined by zymography and tissue inhibitor (TIMP-1) expression was measured by immunoblotting. MMP-9 promoter activity was assessed in transfected ECV304 cells following exposure to isoprenaline or phenylephrine in the absence or presence of either propranolol or prazosin. In patients with heart failure, carvedilol attenuated the increase in proMMP-9 activity observed at 4 and 12 weeks in non-beta-blocker-treated patients (44.0 +/- 4.9 AU versus 60.8 +/- 6.7 AU; P < 0.05). Although TIMP-1 expression was unaltered, the MMP-9:TIMP-1 ratio was lower in those receiving carvedilol at 4 and 12 weeks (0.54 +/- 0.07 versus 1.04 +/- 0.17; P < 0.05). Isoprenaline transiently increased MMP-9 promoter activity after 4 h exposure (80.6 +/- 14.8-fold; P < 0.001) before returning to baseline. The response to isoprenaline was prevented by propranolol (P < 0.01). Phenylephrine caused a biphasic increase in MMP-9 promoter activity, with the greatest increase occurring at 24 h (23 +/- 3.7-fold) compared to baseline. This response was unaffected by co-incubation with prazosin. In conclusion, treatment with a mixed alpha1/beta-adrenoceptor antagonist attenuates MMP activity and tips the degradative balance to a less degradative phenotype in heart failure patients. Furthermore, adrenoceptor stimulation increases MMP-9 promoter activity, which is inhibited by beta- but not alpha-adrenoceptor blockade. Therefore, mixed adrenoceptor blockade may reduce remodeling in heart failure as a direct consequence of a beta-adrenoceptor-mediated reduction in MMP-9 transcription.
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PMID:Adrenoceptor blockade alters plasma gelatinase activity in patients with heart failure and MMP-9 promoter activity in a human cell line (ECV304). 1657 29

Hypertrophic cardiomyocyte growth contributes substantially to the progression of heart failure. Activation of the plasma membrane Na+-H+ exchanger (NHE1) and Cl- -HCO3- exchanger (AE3) has emerged as a central point in the hypertrophic cascade. Both NHE1 and AE3 bind carbonic anhydrase (CA), which activates their transport flux, by providing H+ and HCO3-, their respective transport substrates. We examined the contribution of CA activity to the hypertrophic response of cultured neonatal and adult rodent cardiomyocytes. Phenylephrine (PE) increased cell size by 37 +/- 2% and increased expression of the hypertrophic marker, atrial natriuretic factor mRNA, twofold in cultured neonatal rat cardiomyocytes. Cell size was also increased in adult cardiomyocytes subjected to angiotensin II or PE treatment. These effects were associated with increased expression of cytosolic CAII protein and the membrane-anchored isoform, CAIV. The membrane-permeant CA inhibitor, 6-ethoxyzolamide (ETZ), both prevented and reversed PE-induced hypertrophy in a concentration-dependent manner in neonate cardiomyocytes (IC50=18 microm). ETZ and the related CA inhibitor methazolamide prevented hypertrophy in adult cardiomyocytes. In addition, ETZ inhibited transport activity of NHE1 and the AE isoform, AE3, with respective EC50 values of 1.2 +/- 0.3 microm and 2.7 +/- 0.3 microm. PE significantly increased neonatal cardiomyocyte Ca2+ transient frequency from 0.33 +/- 0.4 Hz to 0.77 +/- 0.04 Hz following 24 h treatment; these Ca2+ -handling abnormalities were completely prevented by ETZ (0.28 +/- 0.07 Hz). Our study demonstrates a novel role for CA in mediating the hypertrophic response of cardiac myocytes to PE and suggests that CA inhibition represents an effective therapeutic approach towards mitigation of the hypertrophic phenotype.
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PMID:Carbonic anhydrase inhibition prevents and reverts cardiomyocyte hypertrophy. 1712 62


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