Journal of molecular and cellular cardiology
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J. Mol. Cell. Cardiol. · Jul 2004
Tumor necrosis factor-alpha does not modulate ischemia/reperfusion injury in naïve myocardium but is essential for the development of late preconditioning.
The role of tumor necrosis factor (TNF)-alpha in myocardial ischemia/reperfusion injury remains controversial. We used homozygous TNF-alpha null mice (TNF-alpha(-/-)) to determine whether TNF-alpha modulates myocardial ischemia/reperfusion injury. Mice were subjected to a 30-min coronary occlusion followed by 24 h of reperfusion. ⋯ While minimal TNF-alpha immunoreactivity was detected in sham-operated hearts, extensive TNF-alpha expression was noted in the cytoplasm of cardiomyocytes in the ischemic/reperfused region 30 min after the PC ischemia. At 30 min after PC, wild-type mice exhibited increased DNA-binding activity of nuclear factor-kappa B (NF-kappa B) and activator protein-1 (AP-1) and nuclear translocation of p65, c-Jun and c-Fos; all of these changes were absent in TNF-alpha(-/-) mice. These data demonstrate that TNF-alpha does not modulate infarct size in the naïve (non-preconditioned) state but is essential for the development of the late phase of ischemic PC, possibly via the activation of NF-kappa B and AP-1 transcription factors.
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J. Mol. Cell. Cardiol. · Jan 2004
Metabolic dysfunction and depletion of mitochondria in hearts of septic rats.
Our previous studies indicate that hearts from septic rats have decreased work with oxygen wasting. The present studies test if there is energy deficit, changes in cardiac mitochondrial content and caspase activation during sepsis. Anesthetized, male Sprague-Dawley rats received no surgical treatment (control), laparotomy (sham), or laparotomy with cecal ligation and puncture (CLP) to induce polymicrobial septic shock. ⋯ Calculated mitochondrial content decreased from 63 +/- 4 mg protein/g wet weight sham to 46 +/- 5 CLP, P < 0.05 (mitochondrial depletion). Caspase-3 activity doubled and tumor necrosis factor alpha content tripled in CLP hearts. CONCLUSIONS. - Oxygen and substrate wasting in CLP occurs with fewer mitochondria and energy deficit, processes that are coincident with caspase-3 activation.
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Recent observations challenged the functional importance or even the existence of mitochondrial ATP-dependent K+ (mitoK(ATP)) channels. In the present study, we determined the presence of K(ATP)-channel subunits in mouse heart mitochondria, and investigated whether known openers or blockers of the channel can alter mitochondrial membrane potential. Investigation of the channel composition was performed with antibodies against K(ATP)-channel subunits, namely the sulfonylurea receptor (SUR1 or SUR2) and the inwardly rectifying K+ channel (Kir6.1 or Kir6.2). ⋯ Mitochondrially formed peroxynitrite is a physiological opener of the channel. We conclude that a functional K(ATP) channel is present in heart mitochondria, which can be opened by diazoxide or BMS-191095. The channel can be composed of Kir6.1 and Kir6.2 subunits and does not contain either SUR1 or SUR2.
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J. Mol. Cell. Cardiol. · Jun 2003
Novel deletions in MYH7 and MYBPC3 identified in Indian families with familial hypertrophic cardiomyopathy.
Mutations causing familial hypertrophic cardiomyopathy (HCM) have been described in at least 11 genes encoding cardiac sarcomeric proteins. In this study, three previously unknown deletions have been identified in the human cardiac genes coding for beta-myosin heavy chain (MYH7 on chromosome 14) and myosin-binding protein-C (MYBPC3 on chromosome 11). In family MM, a 3-bp deletion in MYH7 was detected to be associated with loss of glutamic acid in position 927 (DeltaE927) of the myosin rod. ⋯ It was not seen in 270 Caucasians from Russia and western Europe. Hence, it is considered to represent a regional genetic polymorphism restricted to southern India. The association of the deletion with altered splicing in transfected cells suggests that this deletion may create a "modifying gene", which is per se not or only rarely causing HCM, but which may enhance the phenotype of a mutation responsible for disease.
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J. Mol. Cell. Cardiol. · May 2003
The role of arginine vasopressin and its receptors in the normal and failing rat heart.
To evaluate the role of arginine vasopressin (AVP) in the normal and post-myocardial infarction (post-MI) hearts, and to investigate whether chronic AVP receptor antagonism can attenuate post-infarct ventricular remodeling. ⋯ Isolated adult rat cardiomyocytes bear AVP-V1a receptors that mediate inotropic effects through the IP3 pathway. These receptors are functionally and numerically downregulated in the post-MI remodeled hearts. Despite evidence that AVP is cytotoxic to cells, chronic AVP-V1a receptor blockade does not attenuate post-MI ventricular remodeling in this model. Thus, AVP may not play a major role in the structural progression of HF.