Nitric oxide-dependent and -independent mechanisms are involved in TNF-α-induced depression of cardiac myocyte contractility

2007 ◽  
Vol 292 (5) ◽  
pp. R1900-R1906 ◽  
Author(s):  
Anand Kumar ◽  
Bhanu Paladugu ◽  
Joel Mensing ◽  
Aseem Kumar ◽  
Joseph E. Parrillo

Previous studies have demonstrated the presence of myocardial depression in clinical and experimental septic shock. This response is mediated, in part, through circulating TNF-α-induced, nitric oxide-dependent, depression of basal myocyte contractility. Other mechanisms of early myocardial dysfunction involving decreased response to adrenergic stimulation may exist. This study evaluated the presence and nitric oxide dependence of impaired adrenergic response to TNF-α in in vitro cardiac myocytes. The contraction of electrically paced neonatal rat cardiac myocytes in tissue culture was quantified using a closed-loop video tracking system. TNF-α induced depression of baseline contractility over the first 20 min of cardiac myocyte exposure. This effect was blocked by N-methyl-arginine (NMA), a nitric oxide synthase inhibitor, in all studies. Contractile and cAMP response to increasing concentrations of isoproterenol was deficient in cardiac myocytes exposed to TNF-α regardless of the presence of NMA. In contrast, increasing concentrations of forskolin (a direct stimulant of adenylate cyclase) and dibutyryl cAMP (a metabolically active membrane-soluble analog of cAMP) completely reversed TNF-α-mediated depression, though only in the presence of NMA. Forskolin-stimulated cAMP generation remained intact regardless of NMA. Increasing concentrations of exogenous calcium chloride, unlike other inotropic agents, corrected TNF-α-mediated defects of contractility independent of the presence of NMA. These data suggest that TNF-α exposure is associated with a second nitric oxide-independent but calcium-dependent early depressant mechanism that is manifested by reduced contractile and cAMP response to β-adrenergic stimulation.

1999 ◽  
Vol 276 (1) ◽  
pp. R265-R276 ◽  
Author(s):  
Anand Kumar ◽  
Rupinder Brar ◽  
Peter Wang ◽  
Linda Dee ◽  
Greg Skorupa ◽  
...  

Previous studies have demonstrated the existence of a circulating myocardial depressant substance during human septic shock. We have recently identified this substance as a synergistic combination of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). This study utilized an in vitro cardiac myocyte assay to evaluate the potential mechanistic role of nitric oxide (NO) and cGMP in depression of myocyte contractility induced by TNF-α, IL-1β, TNF-α + IL-1β (at low concentrations), and human septic shock serum (HSS). TNF-α, IL-1β, TNF-α + IL-1β, and each of 5 sera from patients with acute septic shock caused depression of both maximum extent and peak velocity of cardiac myocyte shortening and an increase in intracellular cGMP concentration during 30 min of exposure (minimum P < 0.01). NO synthetase (NOS) and guanylate cyclase inhibitors such as N-methyl-l-arginine (l-NMA) and methylene blue prevented these effects; an excess ofl-arginine withl-NMA restored them (minimum P < 0.01). In contrast,d-arginine failed to reestablish cytokine-induced myocyte depression and cGMP accumulation prevented byl-NMA. Exposure of myocytes to TNF-α, IL-1β, or TNF-α + IL-1β produced a concentration-dependent increase in intracellular cGMP that paralleled the depression of cardiac myocyte contractility (minimum P < 0.001). In addition, TNF-α, IL-1β, TNF-α + IL-1β, or HSS application to cardiac myocytes resulted in increased NO gas generation, which was inhibited byl-NMA (minimum P < 0.01). Furthermore, unstimulated cardiac myocytes were shown to harbor constitutive but not inducible NOS activity. These data suggest that the sequential generation of NO by a constitutive NOS and cGMP by guanylate cyclase represents an important mechanism of cardiac myocyte depression by TNF-α, IL-1β, TNF-α + IL-1β, and the myocardial depressant substance(s) of septic shock.


2009 ◽  
Vol 296 (2) ◽  
pp. H470-H479 ◽  
Author(s):  
Hua Yuan ◽  
Cynthia N. Perry ◽  
Chengqun Huang ◽  
Eri Iwai-Kanai ◽  
Raquel S. Carreira ◽  
...  

Bacterial endotoxin lipopolysaccharide (LPS) is responsible for the multiorgan dysfunction that characterizes septic shock and is causal in the myocardial depression that is a common feature of endotoxemia in patients. In this setting the myocardial dysfunction appears to be due, in part, to the production of proinflammatory cytokines. A line of evidence also indicates that LPS stimulates autophagy in cardiomyocytes. However, the signal transduction pathway leading to autophagy and its role in the heart are incompletely characterized. In this work, we wished to determine the effect of LPS on autophagy and the physiological significance of the autophagic response. Autophagy was monitored morphologically and biochemically in HL-1 cardiomyocytes, neonatal rat cardiomyocytes, and transgenic mouse hearts after the administration of bacterial LPS or TNF-α. We observed that autophagy was increased after exposure to LPS or TNF-α, which is induced by LPS. The inhibition of TNF-α production by AG126 significantly reduced the accumulation of autophagosomes both in cell culture and in vivo. The inhibition of p38 MAPK or nitric oxide synthase by pharmacological inhibitors also reduced autophagy. Nitric oxide or H2O2induced autophagy in cardiomyocytes, whereas N-acetyl-cysteine, a potent antioxidant, suppressed autophagy. LPS resulted in increased reactive oxygen species (ROS) production and decreased total glutathione. To test the hypothesis that autophagy might serve as a damage control mechanism to limit further ROS production, we induced autophagy with rapamycin before LPS exposure. The activation of autophagy by rapamycin suppressed LPS-mediated ROS production and protected cells against LPS toxicity. These findings support the notion that autophagy is a cytoprotective response to LPS-induced cardiomyocyte injury; additional studies are needed to determine the therapeutic implications.


2004 ◽  
Vol 72 (1) ◽  
pp. 359-363 ◽  
Author(s):  
Laura Edith Fichera ◽  
Maria Cecilia Albareda ◽  
Susana Adriana Laucella ◽  
Miriam Postan

ABSTRACT The effect of interleukin-1β (IL-1β), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ) on Trypanosoma cruzi multiplication and nitric oxide (NO) production in cardiac myocytes was investigated. Cardiac myocyte cultures were obtained from neonatal Wistar rat hearts, infected with T. cruzi, and treated with IL-1β, TNF-α, IFN-γ, or N-monomethyl-l-arginine (l-NAME) for 72 h. Parasite growth was calculated from the number of infected cells in Giemsa-stained smears. Nitric oxide production was determined with the Griess reagent. Inducible nitric oxide synthase (iNOS) expression by cardiac myocytes was detected by Western blot. The results showed that the percentages of cardiac myocytes containing T. cruzi amastigotes in cytokine-treated cultures were significantly lower than in nontreated cultures. The addition of l-NAME reversed the inhibitory effect on parasite growth of IL-1β and TNF-α but not of IFN-γ. Nitrite levels released by T. cruzi-infected and noninfected cardiac myocyte cultures after 72 h of stimulation with IL-1β were significantly higher than those produced upon treatment with TNF-α, IFN-γ, or medium alone, regardless of the infection status. Nitrite levels in TNF-α-stimulated infected cultures were significantly higher than in untreated infected cultures and TNF-α-treated noninfected cultures. l-NAME inhibited IL-1β- but not TNF-α-induced NO production, indicating the presence of iNOS-dependent and iNOS-independent mechanisms for NO formation in this experimental system. iNOS expression was detected in infected and noninfected cardiac myocytes stimulated with IL-1 β and TNF-α but not with IFN-γ. These results suggest an important role for cardiac myocytes and locally secreted cytokines in the control of parasite multiplication in T. cruzi-induced myocarditis.


2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Luis Gonano ◽  
Malena Morell ◽  
Juan I Burgos ◽  
Martin Vila Petroff

Cardiac myocyte swelling occurs in multiple pathological situations and in particular contributes to the deleterious effects of ischemia and reperfusion by promoting contractile dysfunction. We investigated whether hypotonic swelling promotes nitric oxide (NO) release in cardiac myocytes and if so, whether it impacts on swelling induced contractile dysfunction. Perfusing rat cardiac myocytes, loaded with the NO sensor DAF-FM, with a hypotonic solution (HS; 217 mOsm), increased cell volume, reduced myocyte contraction and Ca2+ transient amplitude and significantly increased DAF-FM fluorescence. When cells were exposed to the HS supplemented with 2.5 mM of the NO synthase inhibitor L-NAME, cell swelling occurred in the absence of NO release. Swelling-induced NO release was also prevented by the NOS1 inhibitor, Nitroguanidine. In addition, Colchicine (an inhibitor of microtubule polymerization) prevented the increase in DAF-FM fluorescence induced by HS indicating that microtubule integrity is necessary for swelling-induced NO release. The swelling-induced negative inotropic effect was exacerbated in the presence of either L-NAME, Nitroguandine or the guanylate cyclase inhibitor, ODQ, suggesting that NOS1-derived NO provides contractile support via a GMP-dependent mechanism. Indeed, ODQ reduced Ca2+ wave velocity and the HS-induced increment in ryanodine receptor (RyR2) phosphorylation at site Ser2808 suggesting that in the context of hypotonic swelling, cGMP may contribute to preserve contractile function by enhancing SR Ca2+ release. Our findings suggest a novel mechanism for NO release in cardiac myocytes with putative pathophysiological relevance in the context of ischemia and reperfusion, where it may be cardioprotective by reducing the extent of contractile dysfunction associated with hypotonic swelling.


2004 ◽  
Vol 286 (1) ◽  
pp. C1-C7 ◽  
Author(s):  
Hong Kan ◽  
Zirong Xie ◽  
Mitchell S. Finkel

Myocardial dysfunction leading to dilated cardiomyopathy has been documented with surprisingly high frequency in human immunodeficiency virus (HIV)-infected individuals. p38 MAP kinase has been implicated as a mediator of myocardial dysfunction. We previously reported p38 MAP kinase activation by the HIV coat protein gp120 in neonatal rat cardiac myocytes. We now report the direct inotropic effects of HIV gp120 on adult rat ventricular myocytes (ARVM). ARVM were continuously superfused with gp120, and percent fractional shortening (FS) was determined by automated border detection and simultaneous intracellular ionized free Ca2+concentration ([Ca2+]i) measured by fura 2-AM fluorescence: gp120 alone increased FS and increased [Ca2+]iwithin 5 min and then depressed FS without a decrease in [Ca2+]iby 20–60 min, which persisted for at least 2 h. Exposure of ARVM to gp120 also resulted in the phosphorylation of the upstream regulator of p38 MAP kinase MKK3/6, p38 MAP kinase itself, and its downstream effector, ATF-2, over a similar time course. ERK (p44/42) and JNK stress signaling pathways were not similarly activated. The effects of the p38 MAP kinase inhibitor were concentration dependent. SB-203580 (10 μM) blocked both p38 MAP kinase phosphorylation and the delayed negative inotropic effect of gp120. SB-203580 (5 μM) selectively blocked phosphorylation of ATF-2 without blocking the phosphorylation of MKK3/6 or p38 MAP kinase itself. SB-203580 (5 μM) administered before, with, or after gp120 blocked the negative inotropic effect of gp120 in ARVM. p38 MAP kinase activation may be a common stress-response mechanism contributing to myocardial dysfunction in HIV and other nonischemic as well as ischemic cardiomyopathies.


1990 ◽  
Vol 259 (2) ◽  
pp. C325-C331 ◽  
Author(s):  
Y. Miyazaki ◽  
R. W. Gross ◽  
B. E. Sobel ◽  
J. E. Saffitz

To delineate the biochemical mechanisms responsible for the transition from reversible to irreversible ischemic injury, we used quantitative electron microscopic autoradiography. Specific alterations of phospholipid catabolism in individual subcellular organelles of cardiac myocytes associated with simulated ischemic injury were identified. Neonatal rat cardiac myocytes were incubated with 5 nM [3H]arachidonic acid to label loci of phospholipid turnover and were exposed to 30 microM iodoacetate to produce reversible and irreversible injury. Although only minute amounts of arachidonic acid were incorporated into sarcolemmal phospholipids under control conditions, 20- and 96-fold increases were observed under conditions leading to reversible and irreversible cell injury, respectively. Increases of 5- and 28-fold in the specific radioactivity of sarcolemmal phospholipids in reversibly and irreversibly injured cells occurred in the absence of significant alterations in the specific radioactivity of other subcellular compartments, demonstrating that accelerated phospholipid catabolism was confined essentially to the sarcolemma. Selective catabolism of sarcolemmal phospholipids, known to be highly enriched in arachidonic acid, is likely to augment local accumulation of arachidonic acid, identified recently as a second messenger regulating myocardial K+ channels. Because the biochemical integrity of the sarcolemma is critical to both electrophysiological function and viability of myocytes, the observed selective alterations of sarcolemmal phospholipid metabolism appear to be pivotal determinants of lethal myocardial injury.


1995 ◽  
Vol 269 (6) ◽  
pp. H1891-H1898 ◽  
Author(s):  
T. M. McKenna ◽  
S. Li ◽  
S. Tao

Lipopolysaccharide (LPS) treatment impairs cardiac myocyte contractility in a nitric oxide synthase (NOS)-dependent manner. The objective of this study was to assess whether protein kinase C (PKC) transduces the LPS signal into an enhanced NOS activity in rat cardiac myocytes. LPS (100 ng/ml) stimulated myocyte PKC activity, inducible NOS (iNOS) expression, and NOS activity in a time- and protein synthesis-dependent fashion. Directly activating PKC with beta-phorbol 12,13-dibutyrate (beta-PDB) also induced myocyte iNOS synthesis and NOS activity and reduced electrically stimulated contractility, while the inactive alpha-PDB was ineffectual. Contractility could be restored to beta-PDB-incubated cells by superfusion with the NOS inhibitor N omega-nitro-L-arginine methyl ester. PKC blockade with sphingosine, chelerythrine, or calphostin-C precluded LPS- and beta-PDB-induced increases in NOS activity and protected contractility. Depletion of PKC by 18 h of incubation with beta-PDB in the presence of chelerythrine also blocked acquisition of enhanced NOS activity and contractile dysfunction when the myocytes were subsequently exposed to LPS. These findings suggest that PKC is a significant intracellular mediator for the effects of LPS on cardiac cell NOS activity and contractile function.


1995 ◽  
Vol 23 (Supplement) ◽  
pp. A262 ◽  
Author(s):  
Anand Kumar ◽  
Raju Kosuri ◽  
Prasad Kandula ◽  
Linda Dee ◽  
Jeanne Olson ◽  
...  

2014 ◽  
Vol 306 (7) ◽  
pp. C639-C647 ◽  
Author(s):  
Kurt D. Marshall ◽  
Michelle A. Edwards ◽  
Maike Krenz ◽  
J. Wade Davis ◽  
Christopher P. Baines

Cardiac injury induces myocyte apoptosis and necrosis, resulting in the secretion and/or release of intracellular proteins. Currently, myocardial injury can be detected by analysis of a limited number of biomarkers in blood or coronary artery perfusate. However, the complete proteomic signature of protein release from necrotic cardiac myocytes is unknown. Therefore, we undertook a proteomic-based study of proteins released from cultured neonatal rat cardiac myocytes in response to H2O2 (necrosis) or staurosporine (apoptosis) to identify novel specific markers of cardiac myocyte cell death. Necrosis and apoptosis resulted in the identification of 147 and 79 proteins, respectively. Necrosis resulted in a relative increase in the amount of many proteins including the classical necrotic markers lactate dehydrogenase (LDH), high-mobility group B1 (HMGB1), myoglobin, enolase, and 14-3-3 proteins. Additionally, we identified several novel markers of necrosis including HSP90, α-actinin, and Trim72, many of which were elevated over control levels earlier than classical markers of necrotic injury. In contrast, the majority of identified proteins remained at low levels during apoptotic cell death, resulting in no candidate markers for apoptosis being identified. Blotting for a selection of these proteins confirmed their release during necrosis but not apoptosis. We were able to confirm the presence of classical necrotic markers in the extracellular milieu of necrotic myocytes. We also were able to identify novel markers of necrotic cell death with relatively early release profiles compared with classical protein markers of necrosis. These results have implications for the discovery of novel biomarkers of necrotic myocyte injury, especially in the context of ischemia-reperfusion injury.


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